KVM: SVM: Add support for allowing zero SEV ASIDs

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Some BIOSes allow the end user to set the minimum SEV ASID value
(CPUID 0x8000001F_EDX) to be greater than the maximum number of
encrypted guests, or maximum SEV ASID value (CPUID 0x8000001F_ECX)
in order to dedicate all the SEV ASIDs to SEV-ES or SEV-SNP.

The SEV support, as coded, does not handle the case where the minimum
SEV ASID value can be greater than the maximum SEV ASID value.
As a result, the following confusing message is issued:

[   30.715724] kvm_amd: SEV enabled (ASIDs 1007 - 1006)

Fix the support to properly handle this case.

Fixes: 916391a2d1 ("KVM: SVM: Add support for SEV-ES capability in KVM")
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20240104190520.62510-1-Ashish.Kalra@amd.com
Link: https://lore.kernel.org/r/20240131235609.4161407-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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Ashish Kalra 2024-01-31 15:56:08 -08:00 • committed by Sean Christopherson

parent 466eec4a22

commit 0aa6b90ef9

1 changed files with 19 additions and 10 deletions

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arch/x86/kvm/svm/sev.c

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