Commit 7f497775 authored by David Matlack's avatar David Matlack Committed by Paolo Bonzini
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KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes 



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: default avatarDavid Matlack <dmatlack@google.com>
Message-Id: <20220516232138.1783324-6-dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2e65e842

arch/x86/kvm/mmu/mmu.c

+14 −6
Original line number Diff line number Diff line
@@ -3389,10 +3389,11 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, 
	struct kvm_mmu_page *sp;



	role.level = level;



	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;

	}