linux-kernel - [PATCH 22/54] KVM: x86/mmu: Ignore CR0 and CR4 bits in nested EPT MMU role

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Date:   Tue, 22 Jun 2021 10:57:07 -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,
        Yu Zhang <yu.c.zhang@...ux.intel.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 22/54] KVM: x86/mmu: Ignore CR0 and CR4 bits in nested EPT MMU role

Do not incorporate CR0/CR4 bits into the role for the nested EPT MMU, as
EPT behavior is not influenced by CR0/CR4.  Note, this is the guest_mmu,
(L1's EPT), not nested_mmu (L2's IA32 paging); the nested_mmu does need
CR0/CR4, and is initialized in a separate flow.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 241408e6576d..84a40488eba7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4767,8 +4767,10 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 	role.base.guest_mode = true;
 	role.base.access = ACC_ALL;
 
-	role.ext = kvm_calc_mmu_role_ext(vcpu);
+	/* 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;
 }
-- 
2.32.0.288.g62a8d224e6-goog