[PATCH 24/28] KVM: x86/mmu: set CR0.WP=1 for shadow NPT MMU

[Paolo Bonzini <pbonzini@redhat.com>]

The host CR0 does not really reflect onto the NPT format because
hCR0.PG=1 must be set and hCR0.WP is ignored.  Carve that in stone
by removing the cr0 argument from kvm_init_shadow_npt_mmu, and while
at it pass in WP=1 as well.  It does not matter for GMET disabled because
PFERR_USER_MASK is always set, but a cleared W bit in the nested page
tables cannot be overridden in supervisor mode when GMET is enabled,
either.  In fact, since CR0.WP=0 is the weird "extra accesses allowed"
mode, it is actually easier think about it being always set.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/mmu.h        | 4 ++--
 arch/x86/kvm/mmu/mmu.c    | 6 +++---
 arch/x86/kvm/svm/nested.c | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 9031f7ef8e4e..29aa3994a8c2 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -96,8 +96,8 @@ void kvm_mmu_set_me_spte_mask(u64 me_value, u64 me_mask);
 void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_mbec);
 
 void kvm_init_mmu(struct kvm_vcpu *vcpu);
-void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
-			     unsigned long cr4, u64 efer, gpa_t nested_cr3);
+void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
+			     u64 efer, gpa_t nested_cr3);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     int huge_page_level, bool accessed_dirty,
 			     bool mbec, gpa_t new_eptp);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 07b64df8519d..432f0d3ce632 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5933,12 +5933,12 @@ static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu,
 	shadow_mmu_init_context(vcpu, context, cpu_role, root_role);
 }
 
-void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0,
-			     unsigned long cr4, u64 efer, gpa_t nested_cr3)
+void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr4,
+			     u64 efer, gpa_t nested_cr3)
 {
 	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	struct kvm_mmu_role_regs regs = {
-		.cr0 = cr0,
+		.cr0 = X86_CR0_PG | X86_CR0_WP,
 		.cr4 = cr4 & ~X86_CR4_PKE,
 		.efer = efer,
 	};
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index df232153eb24..a1cffd274000 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -93,7 +93,7 @@ static void nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
 	 * when called via KVM_SET_NESTED_STATE, that state may _not_ match current
 	 * vCPU state.  CR0.WP is explicitly ignored, while CR0.PG is required.
 	 */
-	kvm_init_shadow_npt_mmu(vcpu, X86_CR0_PG, svm->vmcb01.ptr->save.cr4,
+	kvm_init_shadow_npt_mmu(vcpu, svm->vmcb01.ptr->save.cr4,
 				svm->vmcb01.ptr->save.efer,
 				svm->nested.ctl.nested_cr3);
 	vcpu->arch.mmu->get_guest_pgd     = nested_svm_get_tdp_cr3;
-- 
2.52.0