linux-kernel - [PATCH 03/23] KVM: MMU: remove valid from extended role

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Date:   Fri,  4 Feb 2022 06:56:58 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     dmatlack@...gle.com, seanjc@...gle.com, vkuznets@...hat.com
Subject: [PATCH 03/23] KVM: MMU: remove valid from extended role

The level field of the MMU role can act as a marker for validity
instead: it is guaranteed to be nonzero so a zero value means 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          | 9 +++------
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index e7e5bd9a984d..4ec7d1e3aa36 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 cr0_pg:1;
 		unsigned int cr4_pae:1;
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b0065ae3cea8..0039b2f21286 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4683,8 +4683,6 @@ static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu,
 		ext.efer_lma = ____is_efer_lma(regs);
 	}
 
-	ext.valid = 1;
-
 	return ext;
 }
 
@@ -4891,7 +4889,6 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 	/* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */
 	role.ext.word = 0;
 	role.ext.execonly = execonly;
-	role.ext.valid = 1;
 
 	return role;
 }
@@ -5039,9 +5036,9 @@ void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu)
 	 * problem is swept under the rug; KVM's CPUID API is horrific and
 	 * it's all but impossible to solve it without introducing a new API.
 	 */
-	vcpu->arch.root_mmu.mmu_role.ext.valid = 0;
-	vcpu->arch.guest_mmu.mmu_role.ext.valid = 0;
-	vcpu->arch.nested_mmu.mmu_role.ext.valid = 0;
+	vcpu->arch.root_mmu.mmu_role.base.level = 0;
+	vcpu->arch.guest_mmu.mmu_role.base.level = 0;
+	vcpu->arch.nested_mmu.mmu_role.base.level = 0;
 	kvm_mmu_reset_context(vcpu);
 
 	/*
-- 
2.31.1