У вт, 2023-08-15 у 14:35 -0700, Sean Christopherson пише:
> Use AVIC_HPA_MASK instead of AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK when
> initializing a vCPU's Physical ID table entry, the two masks are identical.
Masks are identical, but they refer to different things.
AVIC_HPA_MASK is about avic's fields in vmcb, while AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK
is about the portion of the physical id entry which has the address.
They are the same currently but for documentation purposes I don't understand
why removal of one of them makes sense.
IMHO, it's best to define them to the same value, e.g:
#define AVIC_HPA_MASK GENMASK_ULL(51, 12)
#define AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK GENMASK_ULL(51, 12)
Best regards,
Maxim Levitsky
> Keep both #defines for now, along with a few new static asserts. A future
> change will clean up the entire mess (spoiler alert, the masks are
> pointless).
>
> Opportunisitically move the bitwise-OR of AVIC_PHYSICAL_ID_ENTRY_VALID_MASK
> outside of the call to __sme_set(), again to pave the way for code
> deduplication. __sme_set() is purely additive, i.e. ORing in the valid
> bit before or after the C-bit does not change the end result.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/include/asm/svm.h | 2 ++
> arch/x86/kvm/svm/avic.c | 5 ++---
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 1e70600e84f7..609c9b596399 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -285,6 +285,8 @@ static_assert((AVIC_MAX_PHYSICAL_ID & AVIC_PHYSICAL_MAX_INDEX_MASK) == AVIC_MAX_
> static_assert((X2AVIC_MAX_PHYSICAL_ID & AVIC_PHYSICAL_MAX_INDEX_MASK) == X2AVIC_MAX_PHYSICAL_ID);
>
> #define AVIC_HPA_MASK ~((0xFFFULL << 52) | 0xFFF)
> +static_assert(AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK == AVIC_HPA_MASK);
> +static_assert(AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK == GENMASK_ULL(51, 12));
>
> #define SVM_SEV_FEAT_DEBUG_SWAP BIT(5)
>
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 7062164e4041..442c58ef8158 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -308,9 +308,8 @@ static int avic_init_backing_page(struct kvm_vcpu *vcpu)
> if (!entry)
> return -EINVAL;
>
> - new_entry = __sme_set((page_to_phys(svm->avic_backing_page) &
> - AVIC_PHYSICAL_ID_ENTRY_BACKING_PAGE_MASK) |
> - AVIC_PHYSICAL_ID_ENTRY_VALID_MASK);
> + new_entry = __sme_set(page_to_phys(svm->avic_backing_page) & AVIC_HPA_MASK) |
> + AVIC_PHYSICAL_ID_ENTRY_VALID_MASK;
> WRITE_ONCE(*entry, new_entry);
>
> svm->avic_physical_id_cache = entry;