"Unrestricted Guest" feature is added in the VMX specification.
Intel Westmere and onwards processors will support this feature.
It allows kvm guests to run real mode and unpaged mode
code natively in the VMX mode when EPT is turned on. With the
unrestricted guest there is no need to emulate the guest real mode code
in the vm86 container or in the emulator. Also the guest big real mode
code works like native.
The attached patch enhances KVM to use the unrestricted guest feature
if available on the processor. It also adds a new kernel/module
parameter to disable the unrestricted guest feature at the boot time.
Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
VT-x needs an explicit MC vector intercept to handle machine checks in the
hyper visor.
It also has a special option to catch machine checks that happen
during VT entry.
Do these interceptions and forward them to the Linux machine check
handler. Make it always look like user space is interrupted because
the machine check handler treats kernel/user space differently.
Thanks to Jiang Yunhong for help and testing.
Cc: stable@kernel.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
So far KVM only had basic x86 debug register support, once introduced to
realize guest debugging that way. The guest itself was not able to use
those registers.
This patch now adds (almost) full support for guest self-debugging via
hardware registers. It refactors the code, moving generic parts out of
SVM (VMX was already cleaned up by the KVM_SET_GUEST_DEBUG patches), and
it ensures that the registers are properly switched between host and
guest.
This patch also prepares debug register usage by the host. The latter
will (once wired-up by the following patch) allow for hardware
breakpoints/watchpoints in guest code. If this is enabled, the guest
will only see faked debug registers without functionality, but with
content reflecting the guest's modifications.
Tested on Intel only, but SVM /should/ work as well, but who knows...
Known limitations: Trapping on tss switch won't work - most probably on
Intel.
Credits also go to Joerg Roedel - I used his once posted debugging
series as platform for this patch.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
VMX differentiates between processor and software generated exceptions
when injecting them into the guest. Extend vmx_queue_exception
accordingly (and refactor related constants) so that we can use this
service reliably for the new guest debugging framework.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Those definitions will be used by code outside KVM, so move it outside
of a KVM-specific source file.
Those definitions are used only on kvm/vmx.c, that already includes
asm/vmx.h, so they can be moved safely.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
vmx.h will be used by core code that is independent of KVM, so I am
moving it outside the arch/x86/kvm directory.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Nitin A Kamble