KVM: nSVM: Use kvm_rax_read() now that it's mode-aware

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Now that kvm_rax_read() truncates the output value to 32 bits if the
vCPU isn't in 64-bit mode, use it instead of the more verbose (and very
technically slower) kvm_register_read().

Note!  VMLOAD, VMSAVE, and VMRUN emulation are still technically buggy,
as they can use EAX (versus RAX) in 64-bit mode via an operand size
prefix.  Don't bother trying to handle that case, as it would require
decoding the code stream, which would open an entirely different can of
worms, and in practice no sane guest would shove garbage into RAX[63:32]
and then execute VMLOAD/VMSAVE/VMRUN with just EAX.

No functional change intended.

Cc: Yosry Ahmed <yosry@kernel.org>
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260529222223.870923-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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This commit is contained in:

Sean Christopherson 2026-05-29 15:21:53 -07:00

parent 308851c2d6

commit a7e6e09b27

2 changed files with 3 additions and 3 deletions

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arch/x86/kvm/svm/nested.c

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arch/x86/kvm/svm/svm.c

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