KVM: x86: cleanup CR3 reserved bits checks

stable inclusion
from stable-5.10.17
commit 2aba53830f5d02dcd0bb74a00c8b8023df9d1398
bugzilla: 48169

--------------------------------

[ Upstream commit c1c35cf7 ]

If not in long mode, the low bits of CR3 are reserved but not enforced to
be zero, so remove those checks.  If in long mode, however, the MBZ bits
extend down to the highest physical address bit of the guest, excluding
the encryption bit.

Make the checks consistent with the above, and match them between
nested_vmcb_checks and KVM_SET_SREGS.

Cc: stable@vger.kernel.org
Fixes: 761e4169 ("KVM: nSVM: Check that MBZ bits in CR3 and CR4 are not set on vmrun of nested guests")
Fixes: a780a3ea ("KVM: X86: Fix reserved bits check for MOV to CR3")
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

arch/x86/kvm/svm/nested.c

@@ -231,6 +231,7 @@ static bool nested_vmcb_check_controls(struct vmcb_control_area *control)
 
 static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb12)
 {
+	struct kvm_vcpu *vcpu = &svm->vcpu;
 	bool vmcb12_lma;
 
 	if ((vmcb12->save.efer & EFER_SVME) == 0)
@@ -244,18 +245,10 @@ static bool nested_vmcb_checks(struct vcpu_svm *svm, struct vmcb *vmcb12)
 
 	vmcb12_lma = (vmcb12->save.efer & EFER_LME) && (vmcb12->save.cr0 & X86_CR0_PG);
 
-	if (!vmcb12_lma) {
-		if (vmcb12->save.cr4 & X86_CR4_PAE) {
-			if (vmcb12->save.cr3 & MSR_CR3_LEGACY_PAE_RESERVED_MASK)
-				return false;
-		} else {
-			if (vmcb12->save.cr3 & MSR_CR3_LEGACY_RESERVED_MASK)
-				return false;
-		}
-	} else {
+	if (vmcb12_lma) {
 		if (!(vmcb12->save.cr4 & X86_CR4_PAE) ||
 		    !(vmcb12->save.cr0 & X86_CR0_PE) ||
-		    (vmcb12->save.cr3 & MSR_CR3_LONG_MBZ_MASK))
+		    (vmcb12->save.cr3 & vcpu->arch.cr3_lm_rsvd_bits))
 			return false;
 	}
 	if (kvm_valid_cr4(&svm->vcpu, vmcb12->save.cr4))

arch/x86/kvm/svm/svm.h

@@ -346,9 +346,6 @@ static inline bool gif_set(struct vcpu_svm *svm)
 }
 
 /* svm.c */
-#define MSR_CR3_LEGACY_RESERVED_MASK		0xfe7U
-#define MSR_CR3_LEGACY_PAE_RESERVED_MASK	0x7U
-#define MSR_CR3_LONG_MBZ_MASK			0xfff0000000000000U
 #define MSR_INVALID				0xffffffffU
 
 u32 svm_msrpm_offset(u32 msr);

arch/x86/kvm/x86.c

@@ -9628,6 +9628,8 @@ static int kvm_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
 		if (!(sregs->cr4 & X86_CR4_PAE)
 		    || !(sregs->efer & EFER_LMA))
 			return -EINVAL;
+		if (sregs->cr3 & vcpu->arch.cr3_lm_rsvd_bits)
+			return -EINVAL;
 	} else {
 		/*
 		 * Not in 64-bit mode: EFER.LMA is clear and the code