Move the implementations of KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG
for CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT into common KVM code.
The arch specific implemenations are extremely similar, differing
only in whether the dirty log needs to be sync'd from hardware (x86)
and how the TLBs are flushed. Add new arch hooks to handle sync
and TLB flush; the sync will also be used for non-generic dirty log
support in a future patch (s390).
The ulterior motive for providing a common implementation is to
eliminate the dependency between arch and common code with respect to
the memslot referenced by the dirty log, i.e. to make it obvious in the
code that the validity of the memslot is guaranteed, as a future patch
will rework memslot handling such that id_to_memslot() can return NULL.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Now that all callers of kvm_free_memslot() pass NULL for @dont, remove
the param from the top-level routine and all arch's implementations.
No functional change intended.
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Allocate the rmap array during kvm_arch_prepare_memory_region() to pave
the way for removing kvm_arch_create_memslot() altogether. Moving PPC's
memory allocation only changes the order of kernel memory allocations
between PPC and common KVM code.
No functional change intended.
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* Fix compile warning on 32-bit machines
* Fix locking error in secure VM support
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
iQEcBAABCAAGBQJeMiC8AAoJEJ2a6ncsY3GfGg8H/03p+jc/aCKcA75ZeQPlzhmu
KWvSBbPATNcQiYOLfIvbB9AMXUPoyIfiblW/On8G6COFypsIhhUTwEfPUjWIBHNX
IwCfzoyf0gDRTi7A7gTDD06ZE+stikxJu59agX2Gc8kTIQ8ge340VR8J95Ol8/n2
/hVA8S/ORrdv8/KaCcvvIwc1V7OV6xBuGsTUOUvywzBTGDKd0CAbNzRwtS8LmWcM
OCkZX4G5DpFIYdsnjSBaSfwEVPAf3G1DzyQ801emwRnbAGYYgfakd1LwqdLDxptt
6CFHuIENEmmweJKMf9FBLWg+fOMl8wsv9l4mBIYt7coq5XPpi07yJ6yqSaJEToQ=
=Hmfo
-----END PGP SIGNATURE-----
Merge tag 'kvm-ppc-next-5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc into HEAD
Second KVM PPC update for 5.6
* Fix compile warning on 32-bit machines
* Fix locking error in secure VM support
Remove kvm_arch_vcpu_setup() now that all arch specific implementations
are nops.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Fold setup() into create() now that the two are called back-to-back by
common KVM code. This paves the way for removing kvm_arch_vcpu_setup().
Note, BookE directly implements kvm_arch_vcpu_setup() and PPC's common
kvm_arch_vcpu_create() is responsible for its own cleanup, thus the only
cleanup required when directly invoking kvmppc_core_vcpu_setup() is to
call .vcpu_free(), which is the BookE specific portion of PPC's
kvm_arch_vcpu_destroy() by way of kvmppc_core_vcpu_free().
No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move the kvm_cpu_{un}init() calls to common PPC code as an intermediate
step towards removing kvm_cpu_{un}init() altogether.
No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move allocation of all flavors of PPC vCPUs to common PPC code. All
variants either allocate 'struct kvm_vcpu' directly, or require that
the embedded 'struct kvm_vcpu' member be located at offset 0, i.e.
guarantee that the allocation can be directly interpreted as a 'struct
kvm_vcpu' object.
Remove the message from the build-time assertion regarding placement of
the struct, as compatibility with the arch usercopy region is no longer
the sole dependent on 'struct kvm_vcpu' being at offset zero.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Given that in kvm_create_vm() there is:
kvm->mm = current->mm;
And that on every kvm_*_ioctl we have:
if (kvm->mm != current->mm)
return -EIO;
I see no reason to keep using current->mm instead of kvm->mm.
By doing so, we would reduce the use of 'global' variables on code, relying
more in the contents of kvm struct.
Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not write to the free
software foundation 51 franklin street fifth floor boston ma 02110
1301 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 67 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141333.953658117@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, kvm_arch_commit_memory_region() gets called with a
parameter indicating what type of change is being made to the memslot,
but it doesn't pass it down to the platform-specific memslot commit
functions. This adds the `change' parameter to the lower-level
functions so that they can use it in future.
[paulus@ozlabs.org - fix book E also.]
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This patch moves nip/ctr/lr/xer registers from scattered places in
kvm_vcpu_arch to pt_regs structure.
cr register is "unsigned long" in pt_regs and u32 in vcpu->arch.
It will need more consideration and may move in later patches.
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_set_guest_debug().
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_translate().
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_set_sregs().
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_get_sregs().
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_set_regs().
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Move vcpu_load() and vcpu_put() into the architecture specific
implementations of kvm_arch_vcpu_ioctl_get_regs().
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A first step in vcpu->requests encapsulation. Additionally, we now
use READ_ONCE() when accessing vcpu->requests, which ensures we
always load vcpu->requests when it's accessed. This is important as
other threads can change it any time. Also, READ_ONCE() documents
that vcpu->requests is used with other threads, likely requiring
memory barriers, which it does.
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[ Documented the new use of READ_ONCE() and converted another check
in arch/mips/kvm/vz.c ]
Signed-off-by: Andrew Jones <drjones@redhat.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
Users were expected to use kvm_check_request() for testing and clearing,
but request have expanded their use since then and some users want to
only test or do a faster clear.
Make sure that requests are not directly accessed with bit operations.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This provides functions that can be used for generating interrupts
indicating that a given functional unit (floating point, vector, or
VSX) is unavailable. These functions will be used in instruction
emulation code.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We use logical negate where bitwise negate was intended. It means that
we never return -EINVAL here.
Fixes: ce11e48b7f ('KVM: PPC: E500: Add userspace debug stub support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Use the functions from context_tracking.h directly.
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Some wakeups should not be considered a sucessful poll. For example on
s390 I/O interrupts are usually floating, which means that _ALL_ CPUs
would be considered runnable - letting all vCPUs poll all the time for
transactional like workload, even if one vCPU would be enough.
This can result in huge CPU usage for large guests.
This patch lets architectures provide a way to qualify wakeups if they
should be considered a good/bad wakeups in regard to polls.
For s390 the implementation will fence of halt polling for anything but
known good, single vCPU events. The s390 implementation for floating
interrupts does a wakeup for one vCPU, but the interrupt will be delivered
by whatever CPU checks first for a pending interrupt. We prefer the
woken up CPU by marking the poll of this CPU as "good" poll.
This code will also mark several other wakeup reasons like IPI or
expired timers as "good". This will of course also mark some events as
not sucessful. As KVM on z runs always as a 2nd level hypervisor,
we prefer to not poll, unless we are really sure, though.
This patch successfully limits the CPU usage for cases like uperf 1byte
transactional ping pong workload or wakeup heavy workload like OLTP
while still providing a proper speedup.
This also introduced a new vcpu stat "halt_poll_no_tuning" that marks
wakeups that are considered not good for polling.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Radim Krčmář <rkrcmar@redhat.com> (for an earlier version)
Cc: David Matlack <dmatlack@google.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
[Rename config symbol. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The enable_kernel_*() functions leave the relevant MSR bits enabled
until we exit the kernel sometime later. Create disable versions
that wrap the kernel use of FP, Altivec VSX or SPE.
While we don't want to disable it normally for performance reasons
(MSR writes are slow), it will be used for a debug boot option that
does this and catches bad uses in other areas of the kernel.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This new statistic can help diagnosing VCPUs that, for any reason,
trigger bad behavior of halt_poll_ns autotuning.
For example, say halt_poll_ns = 480000, and wakeups are spaced exactly
like 479us, 481us, 479us, 481us. Then KVM always fails polling and wastes
10+20+40+80+160+320+480 = 1110 microseconds out of every
479+481+479+481+479+481+479 = 3359 microseconds. The VCPU then
is consuming about 30% more CPU than it would use without
polling. This would show as an abnormally high number of
attempted polling compared to the successful polls.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com<
Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
On this switch branch the regs initialization
doesn't happen so add it.
This was found with the help of a static
code analysis tool.
Signed-off-by: Laurentiu Tudor <Laurentiu.Tudor@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This lets the function access the new memory slot without going through
kvm_memslots and id_to_memslot. It will simplify the code when more
than one address space will be supported.
Unfortunately, the "const"ness of the new argument must be casted
away in two places. Fixing KVM to accept const struct kvm_memory_slot
pointers would require modifications in pretty much all architectures,
and is left for later.
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Architecture-specific helpers are not supposed to muck with
struct kvm_userspace_memory_region contents. Add const to
enforce this.
In order to eliminate the only write in __kvm_set_memory_region,
the cleaning of deleted slots is pulled up from update_memslots
to __kvm_set_memory_region.
Reviewed-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Reviewed-by: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch introduces a new module parameter for the KVM module; when it
is present, KVM attempts a bit of polling on every HLT before scheduling
itself out via kvm_vcpu_block.
This parameter helps a lot for latency-bound workloads---in particular
I tested it with O_DSYNC writes with a battery-backed disk in the host.
In this case, writes are fast (because the data doesn't have to go all
the way to the platters) but they cannot be merged by either the host or
the guest. KVM's performance here is usually around 30% of bare metal,
or 50% if you use cache=directsync or cache=writethrough (these
parameters avoid that the guest sends pointless flush requests, and
at the same time they are not slow because of the battery-backed cache).
The bad performance happens because on every halt the host CPU decides
to halt itself too. When the interrupt comes, the vCPU thread is then
migrated to a new physical CPU, and in general the latency is horrible
because the vCPU thread has to be scheduled back in.
With this patch performance reaches 60-65% of bare metal and, more
important, 99% of what you get if you use idle=poll in the guest. This
means that the tunable gets rid of this particular bottleneck, and more
work can be done to improve performance in the kernel or QEMU.
Of course there is some price to pay; every time an otherwise idle vCPUs
is interrupted by an interrupt, it will poll unnecessarily and thus
impose a little load on the host. The above results were obtained with
a mostly random value of the parameter (500000), and the load was around
1.5-2.5% CPU usage on one of the host's core for each idle guest vCPU.
The patch also adds a new stat, /sys/kernel/debug/kvm/halt_successful_poll,
that can be used to tune the parameter. It counts how many HLT
instructions received an interrupt during the polling period; each
successful poll avoids that Linux schedules the VCPU thread out and back
in, and may also avoid a likely trip to C1 and back for the physical CPU.
While the VM is idle, a Linux 4 VCPU VM halts around 10 times per second.
Of these halts, almost all are failed polls. During the benchmark,
instead, basically all halts end within the polling period, except a more
or less constant stream of 50 per second coming from vCPUs that are not
running the benchmark. The wasted time is thus very low. Things may
be slightly different for Windows VMs, which have a ~10 ms timer tick.
The effect is also visible on Marcelo's recently-introduced latency
test for the TSC deadline timer. Though of course a non-RT kernel has
awful latency bounds, the latency of the timer is around 8000-10000 clock
cycles compared to 20000-120000 without setting halt_poll_ns. For the TSC
deadline timer, thus, the effect is both a smaller average latency and
a smaller variance.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The kvmppc_get_last_inst function recently received a facelift that allowed
us to pass an enum of the type of instruction we want to read into it rather
than an unreadable boolean.
Unfortunately, not all callers ended up passing the enum. This wasn't really
an issue as "true" and "false" happen to match the two enum values we have,
but it's still hard to read.
Update all callers of kvmppc_get_last_inst() to follow the new calling
convention.
Signed-off-by: Alexander Graf <agraf@suse.de>
This patch extends the use of illegal instruction as software
breakpoint instruction across the ppc platform. Patch extends
booke program interrupt code to support software breakpoint.
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[agraf: Fix bookehv]
Signed-off-by: Alexander Graf <agraf@suse.de>
Powerpc timer implementation is a copycat version of s390. Now that they removed
the tasklet with commit ea74c0ea1b follow this
optimization.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This patch emulates debug registers and debug exception
to support guest using debug resource. This enables running
gdb/kgdb etc in guest.
On BOOKE architecture we cannot share debug resources between QEMU and
guest because:
When QEMU is using debug resources then debug exception must
be always enabled. To achieve this we set MSR_DE and also set
MSRP_DEP so guest cannot change MSR_DE.
When emulating debug resource for guest we want guest
to control MSR_DE (enable/disable debug interrupt on need).
So above mentioned two configuration cannot be supported
at the same time. So the result is that we cannot share
debug resources between QEMU and Guest on BOOKE architecture.
In the current design QEMU gets priority over guest, this means that if
QEMU is using debug resources then guest cannot use them and if guest is
using debug resource then QEMU can overwrite them.
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Make ONE_REG generic for server and embedded architectures by moving
kvm_vcpu_ioctl_get_one_reg() and kvm_vcpu_ioctl_set_one_reg() functions
to powerpc layer.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Add AltiVec support in KVM for Book3e. FPU support gracefully reuse host
infrastructure so follow the same approach for AltiVec.
Book3e specification defines shared interrupt numbers for SPE and AltiVec
units. Still SPE is present in e200/e500v2 cores while AltiVec is present in
e6500 core. So we can currently decide at compile-time which of the SPE or
AltiVec units to support exclusively by using CONFIG_SPE_POSSIBLE and
CONFIG_PPC_E500MC defines. As Alexander Graf suggested, keep SPE and AltiVec
exception handlers distinct to improve code readability.
Guests have the privilege to enable AltiVec, so we always need to support
AltiVec in KVM and implicitly in host to reflect interrupts and to save/restore
the unit context. KVM will be loaded on cores with AltiVec unit only if
CONFIG_ALTIVEC is defined. Use this define to guard KVM AltiVec logic.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Increase FPU laziness by loading the guest state into the unit before entering
the guest instead of doing it on each vcpu schedule. Without this improvement
an interrupt may claim floating point corrupting guest state.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Guest visible debug register and hardware visible debug registers are
same, so ther is no need to have arch->shadow_dbg_reg, instead use
arch->dbg_reg.
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Dbsr is not visible to userspace and we do not think any need to
expose this to userspace because:
Userspace cannot inject debug interrupt to guest (as this
does not know guest ability to handle debug interrupt), so
userspace will always clear DBSR.
Now if userspace has to always clear DBSR in KVM_EXIT_DEBUG
handling then clearing dbsr in kernel looks simple as this
avoid doing SET_SREGS/set_one_reg() to clear DBSR
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Debug interrupt can be either "critical level" or "debug level".
There are separate set of save/restore registers used for different level.
Example: DSRR0/DSRR1 are used for "debug level" and CSRR0/CSRR1
are used for critical level debug interrupt.
Using CPU_FTR_DEBUG_LVL_EXC to decide which interrupt level to be used.
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
DCR handling was only needed for 440 KVM. Since we removed it, we can also
remove handling of DCR accesses.
Signed-off-by: Alexander Graf <agraf@suse.de>
We're going to implement guest code interpretation in KVM for some rare
corner cases. This code needs to be able to inject data and instruction
faults into the guest when it encounters them.
Expose generic APIs to do this in a reasonably subarch agnostic fashion.
Signed-off-by: Alexander Graf <agraf@suse.de>
We have a nice API to find the translated GPAs of a GVA including protection
flags. So far we only use it on Book3S, but there's no reason the same shouldn't
be used on BookE as well.
Implement a kvmppc_xlate() version for BookE and clean it up to make it more
readable in general.
Signed-off-by: Alexander Graf <agraf@suse.de>
On book3e, KVM uses load external pid (lwepx) dedicated instruction to read
guest last instruction on the exit path. lwepx exceptions (DTLB_MISS, DSI
and LRAT), generated by loading a guest address, needs to be handled by KVM.
These exceptions are generated in a substituted guest translation context
(EPLC[EGS] = 1) from host context (MSR[GS] = 0).
Currently, KVM hooks only interrupts generated from guest context (MSR[GS] = 1),
doing minimal checks on the fast path to avoid host performance degradation.
lwepx exceptions originate from host state (MSR[GS] = 0) which implies
additional checks in DO_KVM macro (beside the current MSR[GS] = 1) by looking
at the Exception Syndrome Register (ESR[EPID]) and the External PID Load Context
Register (EPLC[EGS]). Doing this on each Data TLB miss exception is obvious
too intrusive for the host.
Read guest last instruction from kvmppc_load_last_inst() by searching for the
physical address and kmap it. This address the TODO for TLB eviction and
execute-but-not-read entries, and allow us to get rid of lwepx until we are
able to handle failures.
A simple stress benchmark shows a 1% sys performance degradation compared with
previous approach (lwepx without failure handling):
time for i in `seq 1 10000`; do /bin/echo > /dev/null; done
real 0m 8.85s
user 0m 4.34s
sys 0m 4.48s
vs
real 0m 8.84s
user 0m 4.36s
sys 0m 4.44s
A solution to use lwepx and to handle its exceptions in KVM would be to temporary
highjack the interrupt vector from host. This imposes additional synchronizations
for cores like FSL e6500 that shares host IVOR registers between hardware threads.
This optimized solution can be later developed on top of this patch.
Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Sean Christopherson