From: David Matlack <dmatlack@xxxxxxxxxx>
The quadrant is only used when gptes are 4 bytes, but
mmu_alloc_{direct,shadow}_roots() pass in a non-zero quadrant for PAE
page directories regardless. Make this less confusing by only passing in
a non-zero quadrant when it is actually necessary.
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
Message-Id: <20220516232138.1783324-6-dmatlack@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fd1b479bf7fc..f4e7978a6c6a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3389,9 +3389,10 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
struct kvm_mmu_page *sp;
role.level = level;
+ role.quadrant = quadrant;
- if (role.has_4_byte_gpte)
- role.quadrant = quadrant;
+ WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte);
+ WARN_ON_ONCE(role.direct && role.has_4_byte_gpte);
sp = kvm_mmu_get_page(vcpu, gfn, role);
++sp->root_count;
@@ -3427,7 +3428,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
for (i = 0; i < 4; ++i) {
WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
- root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i,
+ root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0,
PT32_ROOT_LEVEL);
mmu->pae_root[i] = root | PT_PRESENT_MASK |
shadow_me_value;
@@ -3512,9 +3513,8 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
struct kvm_mmu *mmu = vcpu->arch.mmu;
u64 pdptrs[4], pm_mask;
gfn_t root_gfn, root_pgd;
+ int quadrant, i, r;
hpa_t root;
- unsigned i;
- int r;
root_pgd = mmu->get_guest_pgd(vcpu);
root_gfn = root_pgd >> PAGE_SHIFT;
@@ -3597,7 +3597,15 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptrs[i] >> PAGE_SHIFT;
}
- root = mmu_alloc_root(vcpu, root_gfn, i, PT32_ROOT_LEVEL);
+ /*
+ * If shadowing 32-bit non-PAE page tables, each PAE page
+ * directory maps one quarter of the guest's non-PAE page
+ * directory. Othwerise each PAE page direct shadows one guest
+ * PAE page directory so that quadrant should be 0.
+ */
+ quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0;
+
+ root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL);
mmu->pae_root[i] = root | pm_mask;
}
--
2.31.1
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