linux-kernel - [PATCH] KVM: x86/mmu: Rename the special lm_root to pml4

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Message-Id: <20210318201131.3242619-1-seanjc@google.com>
Date:   Thu, 18 Mar 2021 13:11:31 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86/mmu: Rename the special lm_root to pml4_root

Rename the lm_root pointer, which is used when shadowing 32-bit L1 NPT
with 64-bit L0 NPT, to pml4_root.  KVM uses dedicated logic to configure
the levels that do not exist in L1's page tables, and to bypass them when
walking the shadow page tables.  That dedicated logic assumes 4-level
paging and will need to be updated if AMD ever gains 5-level paging.

No functional change intended.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/kvm_host.h |  2 +-
 arch/x86/kvm/mmu/mmu.c          | 20 ++++++++++----------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a52f973bdff6..890ada926387 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -396,7 +396,7 @@ struct kvm_mmu {
 	u32 pkru_mask;
 
 	u64 *pae_root;
-	u64 *lm_root;
+	u64 *pml4_root;
 
 	/*
 	 * check zero bits on shadow page table entries, these
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c6ed633594a2..a535fe249cd1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3324,10 +3324,10 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 	if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) {
 		pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
 
-		if (WARN_ON_ONCE(!mmu->lm_root))
+		if (WARN_ON_ONCE(!mmu->pml4_root))
 			return -EIO;
 
-		mmu->lm_root[0] = __pa(mmu->pae_root) | pm_mask;
+		mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask;
 	}
 
 	for (i = 0; i < 4; ++i) {
@@ -3347,7 +3347,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 	}
 
 	if (mmu->shadow_root_level == PT64_ROOT_4LEVEL)
-		mmu->root_hpa = __pa(mmu->lm_root);
+		mmu->root_hpa = __pa(mmu->pml4_root);
 	else
 		mmu->root_hpa = __pa(mmu->pae_root);
 
@@ -3360,7 +3360,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
 static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
-	u64 *lm_root, *pae_root;
+	u64 *pml4_root, *pae_root;
 
 	/*
 	 * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP
@@ -3379,14 +3379,14 @@ static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu)
 	if (WARN_ON_ONCE(mmu->shadow_root_level != PT64_ROOT_4LEVEL))
 		return -EIO;
 
-	if (mmu->pae_root && mmu->lm_root)
+	if (mmu->pae_root && mmu->pml4_root)
 		return 0;
 
 	/*
 	 * The special roots should always be allocated in concert.  Yell and
 	 * bail if KVM ends up in a state where only one of the roots is valid.
 	 */
-	if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->lm_root))
+	if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root))
 		return -EIO;
 
 	/*
@@ -3397,14 +3397,14 @@ static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu)
 	if (!pae_root)
 		return -ENOMEM;
 
-	lm_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
-	if (!lm_root) {
+	pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
+	if (!pml4_root) {
 		free_page((unsigned long)pae_root);
 		return -ENOMEM;
 	}
 
 	mmu->pae_root = pae_root;
-	mmu->lm_root = lm_root;
+	mmu->pml4_root = pml4_root;
 
 	return 0;
 }
@@ -5281,7 +5281,7 @@ static void free_mmu_pages(struct kvm_mmu *mmu)
 	if (!tdp_enabled && mmu->pae_root)
 		set_memory_encrypted((unsigned long)mmu->pae_root, 1);
 	free_page((unsigned long)mmu->pae_root);
-	free_page((unsigned long)mmu->lm_root);
+	free_page((unsigned long)mmu->pml4_root);
 }
 
 static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu)
-- 
2.31.0.rc2.261.g7f71774620-goog