For example, the following could occur, making us miss a wakeup:
CPU0 CPU1
kvm_vcpu_block kvm_mips_comparecount_func
[L] swait_active(&vcpu->wq)
[S] prepare_to_swait(&vcpu->wq)
[L] if (!kvm_vcpu_has_pending_timer(vcpu))
schedule() [S] queue_timer_int(vcpu)
Ensure that the swait_active() check is not hoisted over the interrupt.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If a vcpu exits due to request a user mode spinlock, then
the spinlock-holder may be preempted in user mode or kernel mode.
(Note that not all architectures trap spin loops in user mode,
only AMD x86 and ARM/ARM64 currently do).
But if a vcpu exits in kernel mode, then the holder must be
preempted in kernel mode, so we should choose a vcpu in kernel mode
as a more likely candidate for the lock holder.
This introduces kvm_arch_vcpu_in_kernel() to decide whether the
vcpu is in kernel-mode when it's preempted. kvm_vcpu_on_spin's
new argument says the same of the spinning VCPU.
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Remove code from architecture files that can be moved to virt/kvm, since there
is already common code for coalesced MMIO.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[Removed a pointless 'break' after 'return'.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Create a trace event for guest mode changes, and enable VZ's
GuestCtl0.MC bit after the trace event is enabled to trap all guest mode
changes.
The MC bit causes Guest Hardware Field Change (GHFC) exceptions whenever
a guest mode change occurs (such as an exception entry or return from
exception), so we need to handle this exception now. The MC bit is only
enabled when restoring register state, so enabling the trace event won't
take immediate effect.
Tracing guest mode changes can be particularly handy when trying to work
out what a guest OS gets up to before something goes wrong, especially
if the problem occurs as a result of some previous guest userland
exception which would otherwise be invisible in the trace.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Transfer timer state to the VZ guest context (CP0_GTOffset & guest
CP0_Count) when entering guest mode, enabling direct guest access to it,
and transfer back to soft timer when saving guest register state.
This usually allows guest code to directly read CP0_Count (via MFC0 and
RDHWR) and read/write CP0_Compare, without trapping to the hypervisor
for it to emulate the guest timer. Writing to CP0_Count or CP0_Cause.DC
is much less common and still triggers a hypervisor GPSI exception, in
which case the timer state is transferred back to an hrtimer before
emulating the write.
We are careful to prevent small amounts of drift from building up due to
undeterministic time intervals between reading of the ktime and reading
of CP0_Count. Some drift is expected however, since the system
clocksource may use a different timer to the local CP0_Count timer used
by VZ. This is permitted to prevent guest CP0_Count from appearing to go
backwards.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add the main support for the MIPS Virtualization ASE (A.K.A. VZ) to MIPS
KVM. The bulk of this work is in vz.c, with various new state and
definitions elsewhere.
Enough is implemented to be able to run on a minimal VZ core. Further
patches will fill out support for guest features which are optional or
can be disabled.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
The general guest exit handler needs a few tweaks for VZ compared to
trap & emulate, which for now are made directly depending on
CONFIG_KVM_MIPS_VZ:
- There is no need to re-enable the hardware page table walker (HTW), as
it can be left enabled during guest mode operation with VZ.
- There is no need to perform a privilege check, as any guest privilege
violations should have already been detected by the hardware and
triggered the appropriate guest exception.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Update MIPS KVM entry code to support VZ:
- We need to set GuestCtl0.GM while in guest mode.
- For cores supporting GuestID, we need to set the root GuestID to
match the main GuestID while in guest mode so that the root TLB
refill handler writes the correct GuestID into the TLB.
- For cores without GuestID where the root ASID dealiases RVA/GPA
mappings, we need to load that ASID from the gpa_mm rather than the
per-VCPU guest_kernel_mm or guest_user_mm, since the root TLB maps
guest physical addresses. We also need to restore the normal process
ASID on exit.
- The normal linux process pgd needs restoring on exit, as we can't
leave the GPA mappings active for kernel code.
- GuestCtl0 needs saving on exit for the GExcCode field, as it may be
clobbered if a preemption occurs.
We also need to move the TLB refill handler to the XTLB vector at offset
0x80 on 64-bit VZ kernels, as hardware will use Root.Status.KX to
determine whether a TLB refill or XTLB Refill exception is to be taken
on a root TLB miss from guest mode, and KX needs to be set for kernel
code to be able to access the 64-bit segments.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Abstract the MIPS KVM guest CP0 register access macros into inline
functions which are generated by macros. This allows them to be
generated differently for VZ, where they will usually need to access the
hardware guest CP0 context rather than the saved values in RAM.
Accessors for each individual register are generated using these macros:
- __BUILD_KVM_*_SW() for registers which are not present in the VZ
hardware guest context, so kvm_{read,write}_c0_guest_##name() will
access the saved value in RAM regardless of whether VZ is enabled.
- __BUILD_KVM_*_HW() for registers which are present in the VZ hardware
guest context, so kvm_{read,write}_c0_guest_##name() will access the
hardware register when VZ is enabled.
These build the underlying accessors using further macros:
- __BUILD_KVM_*_SAVED() builds e.g. kvm_{read,write}_sw_gc0_##name()
functions for accessing the saved versions of the registers in RAM.
This is used for implementing the common
kvm_{read,write}_c0_guest_##name() accessors with T&E where registers
are always stored in RAM, but are also available with VZ HW registers
to allow them to be accessed while saved.
- __BUILD_KVM_*_VZ() builds e.g. kvm_{read,write}_vz_gc0_##name()
functions for accessing the VZ hardware guest context registers
directly. This is used for implementing the common
kvm_{read,write}_c0_guest_##name() accessors with VZ.
- __BUILD_KVM_*_WRAP() builds wrappers with different names, which
allows the common kvm_{read,write}_c0_guest_##name() functions to be
implemented using the VZ accessors while still having the SAVED
accessors available too.
- __BUILD_KVM_SAVE_VZ() builds functions for saving and restoring VZ
hardware guest context register state to RAM, improving conciseness
of VZ context saving and restoring.
Similar macros exist for generating modifiers (set, clear, change),
either with a normal unlocked read/modify/write, or using atomic LL/SC
sequences.
These changes change the types of 32-bit registers to u32 instead of
unsigned long, which requires some changes to printk() functions in MIPS
KVM.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add a callback for MIPS KVM implementations to handle the VZ guest
exit exception. Currently the trap & emulate implementation contains a
stub which reports an internal error, but the callback will be used
properly by the VZ implementation.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add an implementation callback for the kvm_arch_hardware_enable() and
kvm_arch_hardware_disable() architecture functions, with simple stubs
for trap & emulate. This is in preparation for VZ which will make use of
them.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add an implementation callback for checking presence of KVM extensions.
This allows implementation specific extensions to be provided without
ifdefs in mips.c.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Currently the software emulated timer is initialised to a frequency of
100MHz by kvm_mips_init_count(), but this isn't suitable for VZ where
the frequency of the guest timer matches that of the host.
Add a count_hz argument so the caller can specify the default frequency,
and move the call from kvm_arch_vcpu_create() to the implementation
specific vcpu_setup() callback, so that VZ can specify a different
frequency.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add new KVM_CAP_MIPS_VZ and KVM_CAP_MIPS_TE capabilities, and in order
to allow MIPS KVM to support VZ without confusing old users (which
expect the trap & emulate implementation), define and start checking
KVM_CREATE_VM type codes.
The codes available are:
- KVM_VM_MIPS_TE = 0
This is the current value expected from the user, and will create a
VM using trap & emulate in user mode, confined to the user mode
address space. This may in future become unavailable if the kernel is
only configured to support VZ, in which case the EINVAL error will be
returned and KVM_CAP_MIPS_TE won't be available even though
KVM_CAP_MIPS_VZ is.
- KVM_VM_MIPS_VZ = 1
This can be provided when the KVM_CAP_MIPS_VZ capability is available
to create a VM using VZ, with a fully virtualized guest virtual
address space. If VZ support is unavailable in the kernel, the EINVAL
error will be returned (although old kernels without the
KVM_CAP_MIPS_VZ capability may well succeed and create a trap &
emulate VM).
This is designed to allow the desired implementation (T&E vs VZ) to be
potentially chosen at runtime rather than being fixed in the kernel
configuration.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Extend MIPS KVM stats counters and kvm_transition trace event codes to
cover hypervisor exceptions, which have their own GExcCode field in
CP0_GuestCtl0 with up to 32 hypervisor exception cause codes.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Update the implementation of kvm_lose_fpu() for VZ, where there is no
need to enable the FPU/MSA in the root context if the FPU/MSA state is
loaded but disabled in the guest context.
The trap & emulate implementation needs to disable FPU/MSA in the root
context when the guest disables them in order to catch the COP1 unusable
or MSA disabled exception when they're used and pass it on to the guest.
For VZ however as long as the context is loaded and enabled in the root
context, the guest can enable and disable it in the guest context
without the hypervisor having to do much, and will take guest exceptions
without hypervisor intervention if used without being enabled in the
guest context.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The purpose of the KVM_SET_SIGNAL_MASK API is to let userspace "kick"
a VCPU out of KVM_RUN through a POSIX signal. A signal is attached
to a dummy signal handler; by blocking the signal outside KVM_RUN and
unblocking it inside, this possible race is closed:
VCPU thread service thread
--------------------------------------------------------------
check flag
set flag
raise signal
(signal handler does nothing)
KVM_RUN
However, one issue with KVM_SET_SIGNAL_MASK is that it has to take
tsk->sighand->siglock on every KVM_RUN. This lock is often on a
remote NUMA node, because it is on the node of a thread's creator.
Taking this lock can be very expensive if there are many userspace
exits (as is the case for SMP Windows VMs without Hyper-V reference
time counter).
As an alternative, we can put the flag directly in kvm_run so that
KVM can see it:
VCPU thread service thread
--------------------------------------------------------------
raise signal
signal handler
set run->immediate_exit
KVM_RUN
check run->immediate_exit
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Increase the maximum number of MIPS KVM VCPUs to 8, and implement the
KVM_CAP_NR_VCPUS and KVM_CAP_MAX_CPUS capabilities which expose the
recommended and maximum number of VCPUs to userland. The previous
maximum of 1 didn't allow for any form of SMP guests.
We calculate the values similarly to ARM, recommending as many VCPUs as
there are CPUs online in the system. This will allow userland to know
how many VCPUs it is possible to create.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Access to various CP0 registers via the KVM register access API needs to
be implementation specific to allow restrictions to be made on changes,
for example when VZ guest registers aren't present, so move them all
into trap_emul.c in preparation for VZ.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Now that load/store faults due to read only memory regions are treated
as MMIO accesses it is safe to claim support for read only memory
regions (KVM_CAP_READONLY_MEM).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Implement the SYNC_MMU capability for KVM MIPS, allowing changes in the
underlying user host virtual address (HVA) mappings to be promptly
reflected in the corresponding guest physical address (GPA) mappings.
This allows for several features to work with guest RAM which require
mappings to be altered or protected, such as copy-on-write, KSM (Kernel
Samepage Merging), idle page tracking, memory swapping, and guest memory
ballooning.
There are two main aspects of this change, described below.
The KVM MMU notifier architecture callbacks are implemented so we can be
notified of changes in the HVA mappings. These arrange for the guest
physical address (GPA) page tables to be modified and possibly for
derived mappings (GVA page tables and TLBs) to be flushed.
- kvm_unmap_hva[_range]() - These deal with HVA mappings being removed,
for example before a copy-on-write takes place, which requires the
corresponding GPA page table mappings to be removed too.
- kvm_set_spte_hva() - These update a GPA page table entry to match the
new HVA entry, but must be careful to respect KVM specific
configuration such as not dirtying a clean guest page which is dirty
to the host, and write protecting writable pages in read only
memslots (which will soon be supported).
- kvm[_test]_age_hva() - These update GPA page table entries to be old
(invalid) so that access can be tracked, making them young again.
The GPA page fault handling (kvm_mips_map_page) is updated to use
gfn_to_pfn_prot() (which may provide read-only pages), to handle
asynchronous page table invalidation from MMU notifier callbacks, and to
handle more cases in the fast path.
- mmu_notifier_seq is used to detect asynchronous page table
invalidations while we're holding a pfn from gfn_to_pfn_prot()
outside of kvm->mmu_lock, retrying if invalidations have taken place,
e.g. a COW or a KSM page merge.
- The fast path (_kvm_mips_map_page_fast) now handles marking old pages
as young / accessed, and disallowing dirtying of clean pages that
aren't actually writable (e.g. shared pages that should COW, and
read-only memory regions when they are enabled in a future patch).
- Due to the use of MMU notifications we no longer need to keep the
page references after we've updated the GPA page tables.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
When an existing memory region has dirty page logging enabled, make the
entire slot clean (read only) so that writes will immediately start
logging dirty pages (once the dirty bit is transferred from GPA to GVA
page tables in an upcoming patch).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
MIPS hasn't up to this point properly supported dirty page logging, as
pages in slots with dirty logging enabled aren't made clean, and tlbmod
exceptions from writes to clean pages have been assumed to be due to
guest TLB protection and unconditionally passed to the guest.
Use the generic dirty logging helper kvm_get_dirty_log_protect() to
properly implement kvm_vm_ioctl_get_dirty_log(), similar to how ARM
does. This uses xchg to clear the dirty bits when reading them, rather
than wiping them out afterwards with a memset, which would potentially
wipe recently set bits that weren't caught by kvm_get_dirty_log(). It
also makes the pages clean again using the
kvm_arch_mmu_enable_log_dirty_pt_masked() architecture callback so that
further writes after the shadow memslot is flushed will trigger tlbmod
exceptions and dirty handling.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Implement the kvm_arch_flush_shadow_all() and
kvm_arch_flush_shadow_memslot() KVM functions for MIPS to allow guest
physical mappings to be safely changed.
The general MIPS KVM code takes care of flushing of GPA page table
entries. kvm_arch_flush_shadow_all() flushes the whole GPA page table,
and is always called on the cleanup path so there is no need to acquire
the kvm->mmu_lock. kvm_arch_flush_shadow_memslot() flushes only the
range of mappings in the GPA page table corresponding to the slot being
flushed, and happens when memory regions are moved or deleted.
MIPS KVM implementation callbacks are added for handling the
implementation specific flushing of mappings derived from the GPA page
tables. These are implemented for trap_emul.c using
kvm_flush_remote_tlbs() which should now be functional, and will flush
the per-VCPU GVA page tables and ASIDS synchronously (before next
entering guest mode or directly accessing GVA space).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Keep the vcpu->mode and vcpu->cpu variables up to date so that
kvm_make_all_cpus_request() has a chance of functioning correctly. This
will soon need to be used for kvm_flush_remote_tlbs().
We can easily update vcpu->cpu when the VCPU context is loaded or saved,
which will happen when accessing guest context and when the guest is
scheduled in and out.
We need to be a little careful with vcpu->mode though, as we will in
future be checking for outstanding VCPU requests, and this must be done
after the value of IN_GUEST_MODE in vcpu->mode is visible to other CPUs.
Otherwise the other CPU could fail to trigger an IPI to wait for
completion dispite the VCPU request not being seen.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Current guest physical memory is mapped to host physical addresses using
a single linear array (guest_pmap of length guest_pmap_npages). This was
only really meant to be temporary, and isn't sparse, so its wasteful of
memory. A small amount of RAM at GPA 0 and a small boot exception vector
at GPA 0x1fc00000 cannot be represented without a full 128KiB guest_pmap
allocation (MIPS32 with 16KiB pages), which is one reason why QEMU
currently runs its boot code at the top of RAM instead of the usual boot
exception vector address.
Instead use the existing infrastructure for host virtual page table
management to allocate a page table for guest physical memory too. This
should be sufficient for now, assuming the size of physical memory
doesn't exceed the size of virtual memory. It may need extending in
future to handle XPA (eXtended Physical Addressing) in 32-bit guests, as
supported by VZ guests on P5600.
Some of this code is based loosely on Cavium's VZ KVM implementation.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
When exiting from the guest, store the values of the CP0_BadInstr and
CP0_BadInstrP registers if they exist, which contain the encodings of
the instructions which caused the last synchronous exception.
When the instruction is needed for emulation, kvm_get_badinstr() and
kvm_get_badinstrp() are used instead of calling kvm_get_inst() directly,
to decide whether to read the saved CP0_BadInstr/CP0_BadInstrP registers
(if they exist), or read the instruction from memory (if not).
The use of these registers should be more robust than using
kvm_get_inst(), as it actually gives the instruction encoding seen by
the hardware rather than relying on user accessors after the fact, which
can be fooled by incoherent icache or a racing code modification. It
will also work with VZ, where the guest virtual memory isn't directly
accessible by the host with user accessors.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Currently kvm_get_inst() returns KVM_INVALID_INST in the event of a
fault reading the guest instruction. This has the rather arbitrary magic
value 0xdeadbeef. This API isn't very robust, and in fact 0xdeadbeef is
a valid MIPS64 instruction encoding, namely "ld t1,-16657(s5)".
Therefore change the kvm_get_inst() API to return 0 or -EFAULT, and to
return the instruction via a u32 *out argument. We can then drop the
KVM_INVALID_INST definition entirely.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Now that the commpage doesn't use wired TLB entries, the per-CPU
vm_init() callback is the only work done by kvm_mips_init_vm_percpu().
The trap & emulate implementation doesn't actually need to do anything
from vm_init(), and the future VZ implementation would be better served
by a kvm_arch_hardware_enable callback anyway.
Therefore drop the vm_init() callback entirely, allowing the
kvm_mips_init_vm_percpu() function to also be dropped, along with the
kvm_mips_instance atomic counter.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Now that we have GVA page tables and an optimised TLB refill handler in
place, convert the handling of commpage faults from the guest kernel to
fill the GVA page table and invalidate the TLB entry, rather than
filling the wired TLB entry directly.
For simplicity we no longer use a wired entry for the commpage (refill
should be much cheaper with the fast-path handler anyway). Since we
don't need to manipulate the TLB directly any longer, move the function
from tlb.c to mmu.c. This puts it closer to the similar functions
handling KSeg0 and TLB mapped page faults from the guest.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Implement invalidation of specific pairs of GVA page table entries in
one or both of the GVA page tables. This is used when existing mappings
are replaced in the guest TLB by emulated TLBWI/TLBWR instructions. Due
to the sharing of page tables in the host kernel range, we should be
careful not to allow host pages to be invalidated.
Add a helper kvm_mips_walk_pgd() which can be used when walking of
either GPA (future patches) or GVA page tables is needed, optionally
with allocation of page tables along the way when they don't exist.
GPA page table walking will need to be protected by the kvm->mmu_lock,
so we also add a small MMU page cache in each KVM VCPU, like that found
for other architectures but smaller. This allows enough pages to be
pre-allocated to handle a single fault without holding the lock,
allowing the helper to run with the lock held without having to handle
allocation failures.
Using the same mechanism for GVA allows the same code to be used, and
allows it to use the same cache of allocated pages if the GPA walk
didn't need to allocate any new tables.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Use functions from the general MIPS TLB exception vector generation code
(tlbex.c) to construct a fast path TLB refill handler similar to the
general one, but cut down and capable of preserving K0 and K1.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Allocate GVA -> HPA page tables for guest kernel and guest user mode on
each VCPU, to allow for fast path TLB refill handling to be added later.
In the process kvm_arch_vcpu_init() needs updating to pass on any error
from the vcpu_init() callback.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Wire up a vcpu uninit implementation callback. This will be used for the
clean up of GVA->HPA page tables.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Add implementation callbacks for entering the guest (vcpu_run()) and
reentering the guest (vcpu_reenter()), allowing implementation specific
operations to be performed before entering the guest or after returning
to the host without cluttering kvm_arch_vcpu_ioctl_run().
This allows the T&E specific lazy user GVA flush to be moved into
trap_emul.c, along with disabling of the HTW. We also move
kvm_mips_deliver_interrupts() as VZ will need to restore the guest timer
state prior to delivering interrupts.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
The kvm_vcpu_arch structure contains both mm_structs for allocating MMU
contexts (primarily the ASID) but it also copies the resulting ASIDs
into guest_{user,kernel}_asid[] arrays which are referenced from uasm
generated code.
This duplication doesn't seem to serve any purpose, and it gets in the
way of generalising the ASID handling across guest kernel/user modes, so
lets just extract the ASID straight out of the mm_struct on demand, and
in fact there are convenient cpu_context() and cpu_asid() macros for
doing so.
To reduce the verbosity of this code we do also add kern_mm and user_mm
local variables where the kernel and user mm_structs are used.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
MIPS incompletely implements the KVM_NMI ioctl to supposedly perform a
CPU reset, but all it actually does is invalidate the ASIDs. It doesn't
expose the KVM_CAP_USER_NMI capability which is supposed to indicate the
presence of the KVM_NMI ioctl, and no user software actually uses it on
MIPS.
Since this is dead code that would technically need updating for GVA
page table handling in upcoming patches, remove it now. If we wanted to
implement NMI injection later it can always be done properly along with
the KVM_CAP_USER_NMI capability, and if we wanted to implement a proper
CPU reset it would be better done with a separate ioctl.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
* Return directly after a call of the function "copy_from_user" failed
in a case block.
* Delete the jump label "out" which became unnecessary with
this refactoring.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Flush the KVM entry code from the icache on all CPUs, not just the one
that built the entry code.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org> # 3.16.x-
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
kvm_mips_check_asids() runs before entering the guest and performs lazy
regeneration of host ASID for guest usermode, using last_user_gasid to
track the last guest ASID in the VCPU that was used by guest usermode on
any host CPU.
last_user_gasid is reset after performing the lazy ASID regeneration on
the current CPU, and by kvm_arch_vcpu_load() if the host ASID for guest
usermode is regenerated due to staleness (to cancel outstanding lazy
ASID regenerations). Unfortunately neither case handles SMP hosts
correctly:
- When the lazy ASID regeneration is performed it should apply to all
CPUs (as last_user_gasid does), so reset the ASID on other CPUs to
zero to trigger regeneration when the VCPU is next loaded on those
CPUs.
- When the ASID is found to be stale on the current CPU, we should not
cancel lazy ASID regenerations globally, so drop the reset of
last_user_gasid altogether here.
Both cases would require a guest ASID change and two host CPU migrations
(and in the latter case one of the CPUs to start a new ASID cycle)
before guest usermode could potentially access stale user pages from a
previously running ASID in the same VCPU.
Fixes: 25b08c7fb0 ("KVM: MIPS: Invalidate TLB by regenerating ASIDs")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MIPS KVM uses user memory accessors but mips.c doesn't directly include
uaccess.h, so include it now.
This wasn't too much of a problem before v4.9-rc1 as asm/module.h
included asm/uaccess.h, however since commit 29abfbd9cb ("mips:
separate extable.h, switch module.h to it") this is no longer the case.
This resulted in build failures when trace points were disabled, as
trace/define_trace.h includes trace/trace_events.h only ifdef
TRACEPOINTS_ENABLED, which goes on to include asm/uaccess.h via a couple
of other headers.
Fixes: 29abfbd9cb ("mips: separate extable.h, switch module.h to it")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Invalidate host TLB mappings when the guest ASID is changed by
regenerating ASIDs, rather than flushing the entire host TLB except
entries in the guest KSeg0 range.
For the guest kernel mode ASID we regenerate on the spot when the guest
ASID is changed, as that will always take place while the guest is in
kernel mode.
However when the guest invalidates TLB entries the ASID will often by
changed temporarily as part of writing EntryHi without the guest
returning to user mode in between. We therefore regenerate the user mode
ASID lazily before entering the guest in user mode, if and only if the
guest ASID has actually changed since the last guest user mode entry.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Two stubs are added:
o kvm_arch_has_vcpu_debugfs(): must return true if the arch
supports creating debugfs entries in the vcpu debugfs dir
(which will be implemented by the next commit)
o kvm_arch_create_vcpu_debugfs(): code that creates debugfs
entries in the vcpu debugfs dir
For x86, this commit introduces a new file to avoid growing
arch/x86/kvm/x86.c even more.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fail if the address of the allocated exception base doesn't fit into the
CP0_EBase register. This can happen on MIPS64 if CP0_EBase.WG isn't
implemented but RAM is available outside of the range of KSeg0.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
MIPSr6 doesn't have lo/hi registers, so don't bother saving or
restoring them, and don't expose them to userland with the KVM ioctl
interface either.
In fact the lo/hi registers aren't callee saved in the MIPS ABIs anyway,
so there is no need to preserve the host lo/hi values at all when
transitioning to and from the guest (which happens via a function call).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use a relative branch to get from the individual exception vectors to
the common guest exit handler, rather than loading the address of the
exit handler and jumping to it.
This is made easier due to the fact we are now generating the entry code
dynamically. This will also allow the exception code to be further
reduced in future patches.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Scratch cop0 registers are needed by KVM to be able to save/restore all
the GPRs, including k0/k1, and for storing the VCPU pointer. However no
registers are universally suitable for these purposes, so the decision
should be made at runtime.
Until now, we've used DDATA_LO to store the VCPU pointer, and ErrorEPC
as a temporary. It could be argued that this is abuse of those
registers, and DDATA_LO is known not to be usable on certain
implementations (Cavium Octeon). If KScratch registers are present, use
them instead.
We save & restore the temporary register in addition to the VCPU pointer
register when using a KScratch register for it, as it may be used for
normal host TLB handling too.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Dump the generated entry code with pr_debug(), similar to how it is done
in tlbex.c, so it can be more easily debugged.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Davidlohr Bueso