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SubjectRe: [PATCH 02/16] KVM: x86: Remove separate "bit" defines for page fault error code masks
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I remember I read somewhere suggesting not to change the headers in selftest.

Just double-check if there is requirement to edit
tools/testing/selftests/kvm/include/x86_64/processor.h.

Dongli Zhang

On 2/27/24 18:41, Sean Christopherson wrote:
> Open code the bit number directly in the PFERR_* masks and drop the
> intermediate PFERR_*_BIT defines, as having to bounce through two macros
> just to see which flag corresponds to which bit is quite annoying, as is
> having to define two macros just to add recognition of a new flag.
>
> Use ilog2() to derive the bit in permission_fault(), the one function that
> actually needs the bit number (it does clever shifting to manipulate flags
> in order to avoid conditional branches).
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/include/asm/kvm_host.h | 32 ++++++++++----------------------
> arch/x86/kvm/mmu.h | 4 ++--
> 2 files changed, 12 insertions(+), 24 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index aaf5a25ea7ed..88cc523bafa8 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -254,28 +254,16 @@ enum x86_intercept_stage;
> KVM_GUESTDBG_INJECT_DB | \
> KVM_GUESTDBG_BLOCKIRQ)
>
> -
> -#define PFERR_PRESENT_BIT 0
> -#define PFERR_WRITE_BIT 1
> -#define PFERR_USER_BIT 2
> -#define PFERR_RSVD_BIT 3
> -#define PFERR_FETCH_BIT 4
> -#define PFERR_PK_BIT 5
> -#define PFERR_SGX_BIT 15
> -#define PFERR_GUEST_FINAL_BIT 32
> -#define PFERR_GUEST_PAGE_BIT 33
> -#define PFERR_IMPLICIT_ACCESS_BIT 48
> -
> -#define PFERR_PRESENT_MASK BIT(PFERR_PRESENT_BIT)
> -#define PFERR_WRITE_MASK BIT(PFERR_WRITE_BIT)
> -#define PFERR_USER_MASK BIT(PFERR_USER_BIT)
> -#define PFERR_RSVD_MASK BIT(PFERR_RSVD_BIT)
> -#define PFERR_FETCH_MASK BIT(PFERR_FETCH_BIT)
> -#define PFERR_PK_MASK BIT(PFERR_PK_BIT)
> -#define PFERR_SGX_MASK BIT(PFERR_SGX_BIT)
> -#define PFERR_GUEST_FINAL_MASK BIT_ULL(PFERR_GUEST_FINAL_BIT)
> -#define PFERR_GUEST_PAGE_MASK BIT_ULL(PFERR_GUEST_PAGE_BIT)
> -#define PFERR_IMPLICIT_ACCESS BIT_ULL(PFERR_IMPLICIT_ACCESS_BIT)
> +#define PFERR_PRESENT_MASK BIT(0)
> +#define PFERR_WRITE_MASK BIT(1)
> +#define PFERR_USER_MASK BIT(2)
> +#define PFERR_RSVD_MASK BIT(3)
> +#define PFERR_FETCH_MASK BIT(4)
> +#define PFERR_PK_MASK BIT(5)
> +#define PFERR_SGX_MASK BIT(15)
> +#define PFERR_GUEST_FINAL_MASK BIT_ULL(32)
> +#define PFERR_GUEST_PAGE_MASK BIT_ULL(33)
> +#define PFERR_IMPLICIT_ACCESS BIT_ULL(48)
>
> #define PFERR_NESTED_GUEST_PAGE (PFERR_GUEST_PAGE_MASK | \
> PFERR_WRITE_MASK | \
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 60f21bb4c27b..e8b620a85627 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -213,7 +213,7 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
> */
> u64 implicit_access = access & PFERR_IMPLICIT_ACCESS;
> bool not_smap = ((rflags & X86_EFLAGS_AC) | implicit_access) == X86_EFLAGS_AC;
> - int index = (pfec + (not_smap << PFERR_RSVD_BIT)) >> 1;
> + int index = (pfec + (not_smap << ilog2(PFERR_RSVD_MASK))) >> 1;
> u32 errcode = PFERR_PRESENT_MASK;
> bool fault;
>
> @@ -235,7 +235,7 @@ static inline u8 permission_fault(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
>
> /* clear present bit, replace PFEC.RSVD with ACC_USER_MASK. */
> offset = (pfec & ~1) +
> - ((pte_access & PT_USER_MASK) << (PFERR_RSVD_BIT - PT_USER_SHIFT));
> + ((pte_access & PT_USER_MASK) << (ilog2(PFERR_RSVD_MASK) - PT_USER_SHIFT));
>
> pkru_bits &= mmu->pkru_mask >> offset;
> errcode |= -pkru_bits & PFERR_PK_MASK;

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