linux-kernel - [PATCH 06/23] KVM: MMU: load new PGD once nested two-dimensional paging is initialized

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Date:   Fri,  4 Feb 2022 06:57:01 -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 06/23] KVM: MMU: load new PGD once nested two-dimensional paging is initialized

__kvm_mmu_new_pgd looks at the MMU's root_level and shadow_root_level
via fast_pgd_switch.  It makes no sense to call it before updating
these fields, even though it was done like that ever since nested
VMX grew the ability to use fast CR3 switch (commit 50c28f21d045,
"kvm: x86: Use fast CR3 switch for nested VMX").

Pull it to the end of the initialization of the shadow nested MMUs.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu/mmu.c | 41 +++++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 577e70509510..b8ab16323629 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4869,10 +4869,9 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
 
 	new_role = kvm_calc_shadow_npt_root_page_role(vcpu, &regs);
 
-	__kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base);
-
 	shadow_mmu_init_context(vcpu, context, &regs, new_role);
 	reset_shadow_zero_bits_mask(vcpu, context, is_efer_nx(context));
+	__kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base);
 }
 EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu);
 
@@ -4906,27 +4905,25 @@ void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 		kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty,
 						   execonly, level);
 
-	__kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base);
-
-	if (new_role.as_u64 == context->mmu_role.as_u64)
-		return;
-
-	context->mmu_role.as_u64 = new_role.as_u64;
-
-	context->shadow_root_level = level;
-
-	context->ept_ad = accessed_dirty;
-	context->page_fault = ept_page_fault;
-	context->gva_to_gpa = ept_gva_to_gpa;
-	context->sync_page = ept_sync_page;
-	context->invlpg = ept_invlpg;
-	context->root_level = level;
-	context->direct_map = false;
+	if (new_role.as_u64 != context->mmu_role.as_u64) {
+		context->mmu_role.as_u64 = new_role.as_u64;
+
+		context->shadow_root_level = level;
+
+		context->ept_ad = accessed_dirty;
+		context->page_fault = ept_page_fault;
+		context->gva_to_gpa = ept_gva_to_gpa;
+		context->sync_page = ept_sync_page;
+		context->invlpg = ept_invlpg;
+		context->root_level = level;
+		context->direct_map = false;
+		update_permission_bitmask(context, true);
+		context->pkru_mask = 0;
+		reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level);
+		reset_ept_shadow_zero_bits_mask(context, execonly);
+	}
 
-	update_permission_bitmask(context, true);
-	context->pkru_mask = 0;
-	reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level);
-	reset_ept_shadow_zero_bits_mask(context, execonly);
+	__kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base);
 }
 EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);
 
-- 
2.31.1