linux-kernel - [PATCH 02/16] KVM: x86: Remove separate "bit" defines for page fault error code masks

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Date: Tue, 27 Feb 2024 18:41:33 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yan Zhao <yan.y.zhao@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>, 
	Michael Roth <michael.roth@....com>, Yu Zhang <yu.c.zhang@...ux.intel.com>, 
	Chao Peng <chao.p.peng@...ux.intel.com>, Fuad Tabba <tabba@...gle.com>, 
	David Matlack <dmatlack@...gle.com>
Subject: [PATCH 02/16] KVM: x86: Remove separate "bit" defines for page fault
 error code masks

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@...gle.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;
-- 
2.44.0.278.ge034bb2e1d-goog