linux-kernel - [PATCH v2 18/25] KVM: x86/mmu: remove valid from extended role

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Date:   Mon, 21 Feb 2022 11:22:36 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     dmatlack@...gle.com, seanjc@...gle.com
Subject: [PATCH v2 18/25] KVM: x86/mmu: remove valid from extended role

The level and direct field of the CPU mode can act as a marker for validity
instead: exactly one of them is guaranteed to be nonzero, so a zero value
for both means that the role is invalid and the MMU properties will be
computed again.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/include/asm/kvm_host.h | 4 +---
 arch/x86/kvm/mmu/mmu.c          | 8 +++-----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 14f391582738..b8b115b2038f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -342,8 +342,7 @@ union kvm_mmu_page_role {
  * kvm_mmu_extended_role complements kvm_mmu_page_role, tracking properties
  * relevant to the current MMU configuration.   When loading CR0, CR4, or EFER,
  * including on nested transitions, if nothing in the full role changes then
- * MMU re-configuration can be skipped. @valid bit is set on first usage so we
- * don't treat all-zero structure as valid data.
+ * MMU re-configuration can be skipped.
  *
  * The properties that are tracked in the extended role but not the page role
  * are for things that either (a) do not affect the validity of the shadow page
@@ -360,7 +359,6 @@ union kvm_mmu_page_role {
 union kvm_mmu_extended_role {
 	u32 word;
 	struct {
-		unsigned int valid:1;
 		unsigned int execonly:1;
 		unsigned int cr4_pse:1;
 		unsigned int cr4_pke:1;
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index eb7c62c11700..d657e2e2ceec 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4699,7 +4699,6 @@ kvm_calc_cpu_mode(struct kvm_vcpu *vcpu, const struct kvm_mmu_role_regs *regs)
 		role.ext.efer_lma = ____is_efer_lma(regs);
 	}
 
-	role.ext.valid = 1;
 	return role;
 }
 
@@ -4874,7 +4873,6 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 
 	role.ext.word = 0;
 	role.ext.execonly = execonly;
-	role.ext.valid = 1;
 
 	return role;
 }
@@ -4994,9 +4992,9 @@ void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	vcpu->arch.root_mmu.root_role.word = 0;
 	vcpu->arch.guest_mmu.root_role.word = 0;
 	vcpu->arch.nested_mmu.root_role.word = 0;
-	vcpu->arch.root_mmu.cpu_mode.ext.valid = 0;
-	vcpu->arch.guest_mmu.cpu_mode.ext.valid = 0;
-	vcpu->arch.nested_mmu.cpu_mode.ext.valid = 0;
+	vcpu->arch.root_mmu.cpu_mode.as_u64 = 0;
+	vcpu->arch.guest_mmu.cpu_mode.as_u64 = 0;
+	vcpu->arch.nested_mmu.cpu_mode.as_u64 = 0;
 	kvm_mmu_reset_context(vcpu);
 
 	/*
-- 
2.31.1