KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure

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Currently, an SEV-ES guest is terminated if the validation of the VMGEXIT
exit code or exit parameters fails.

The VMGEXIT instruction can be issued from userspace, even though
userspace (likely) can't update the GHCB. To prevent userspace from being
able to kill the guest, return an error through the GHCB when validation
fails rather than terminating the guest. For cases where the GHCB can't be
updated (e.g. the GHCB can't be mapped, etc.), just return back to the
guest.

The new error codes are documented in the lasest update to the GHCB
specification.

Fixes: 291bd20d5d ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <b57280b5562893e2616257ac9c2d4525a9aeeb42.1638471124.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Tom Lendacky 2021-12-02 12:52:05 -06:00 • committed by Paolo Bonzini

parent a655276a59

commit ad5b353240

2 changed files with 71 additions and 46 deletions

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11

arch/x86/include/asm/sev-common.h

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106

arch/x86/kvm/svm/sev.c

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