KVM: nSVM: Fail emulation of VMRUN/VMLOAD/VMSAVE if mapping vmcb12 fails

Browse source

KVM currently injects a #GP if mapping vmcb12 fails when emulating
VMRUN/VMLOAD/VMSAVE. This is not architectural behavior, as #GP should
only be injected if the physical address is not supported or not
aligned. Instead, handle it as an emulation failure, similar to how nVMX
handles failures to read/write guest memory in several emulation paths.

When virtual VMLOAD/VMSAVE is enabled, if vmcb12's GPA is not mapped in
the NPTs a VMEXIT(#NPF) will be generated, and KVM will install an MMIO
SPTE and emulate the instruction if there is no corresponding memslot.
x86_emulate_insn() will return EMULATION_FAILED as VMLOAD/VMSAVE are not
handled as part of the twobyte_insn cases.

Even though this will also result in an emulation failure, it will only
result in a straight return to userspace if
KVM_CAP_EXIT_ON_EMULATION_FAILURE is set. Otherwise, it would inject #UD
and only exit to userspace if not in guest mode. So the behavior is
slightly different if virtual VMLOAD/VMSAVE is enabled.

Fixes: 3d6368ef58 ("KVM: SVM: Add VMRUN handler")
Reported-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260316202732.3164936-8-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

...

This commit is contained in:

Yosry Ahmed 2026-03-16 20:27:30 +00:00 • committed by Sean Christopherson

parent 878b8efa2a

commit 2daf71bfd7

2 changed files with 4 additions and 8 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

6

arch/x86/kvm/svm/nested.c

View file

6

arch/x86/kvm/svm/svm.c

View file