[PATCH] KVM: x86: introduce is_pae_paging

[PATCH] KVM: x86: introduce is_pae_paging

[Paolo Bonzini]

Checking for 32-bit PAE is quite common around code that fiddles with
the PDPTRs.  Add a function to compress all checks into a single
invocation.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx/nested.c | 3 +--
 arch/x86/kvm/vmx/vmx.c    | 4 ++--
 arch/x86/kvm/x86.c        | 8 ++++----
 arch/x86/kvm/x86.h        | 5 +++++
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index be8afec29f68..33b2c0570419 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -962,8 +962,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
 		 * If PAE paging and EPT are both on, CR3 is not used by the CPU and
 		 * must not be dereferenced.
 		 */
-		if (!is_long_mode(vcpu) && is_pae(vcpu) && is_paging(vcpu) &&
-		    !nested_ept) {
+		if (is_pae_paging(vcpu) && !nested_ept) {
 			if (!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)) {
 				*entry_failure_code = ENTRY_FAIL_PDPTE;
 				return -EINVAL;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c03396525e3b..70bcfbd1a4b0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2768,7 +2768,7 @@ static void ept_load_pdptrs(struct kvm_vcpu *vcpu)
 		      (unsigned long *)&vcpu->arch.regs_dirty))
 		return;
 
-	if (is_paging(vcpu) && is_pae(vcpu) && !is_long_mode(vcpu)) {
+	if (is_pae_paging(vcpu)) {
 		vmcs_write64(GUEST_PDPTR0, mmu->pdptrs[0]);
 		vmcs_write64(GUEST_PDPTR1, mmu->pdptrs[1]);
 		vmcs_write64(GUEST_PDPTR2, mmu->pdptrs[2]);
@@ -2780,7 +2780,7 @@ void ept_save_pdptrs(struct kvm_vcpu *vcpu)
 {
 	struct kvm_mmu *mmu = vcpu->arch.walk_mmu;
 
-	if (is_paging(vcpu) && is_pae(vcpu) && !is_long_mode(vcpu)) {
+	if (is_pae_paging(vcpu)) {
 		mmu->pdptrs[0] = vmcs_read64(GUEST_PDPTR0);
 		mmu->pdptrs[1] = vmcs_read64(GUEST_PDPTR1);
 		mmu->pdptrs[2] = vmcs_read64(GUEST_PDPTR2);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 88489af13e96..2da741329f6d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -719,7 +719,7 @@ bool pdptrs_changed(struct kvm_vcpu *vcpu)
 	gfn_t gfn;
 	int r;
 
-	if (is_long_mode(vcpu) || !is_pae(vcpu) || !is_paging(vcpu))
+	if (!is_pae_paging(vcpu))
 		return false;
 
 	if (!test_bit(VCPU_EXREG_PDPTR,
@@ -962,8 +962,8 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 	if (is_long_mode(vcpu) &&
 	    (cr3 & rsvd_bits(cpuid_maxphyaddr(vcpu), 63)))
 		return 1;
-	else if (is_pae(vcpu) && is_paging(vcpu) &&
-		   !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
+	else if (is_pae_paging(vcpu) &&
+		 !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))
 		return 1;
 
 	kvm_mmu_new_cr3(vcpu, cr3, skip_tlb_flush);
@@ -8596,7 +8596,7 @@ static int __set_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
 		kvm_update_cpuid(vcpu);
 
 	idx = srcu_read_lock(&vcpu->kvm->srcu);
-	if (!is_long_mode(vcpu) && is_pae(vcpu) && is_paging(vcpu)) {
+	if (is_pae_paging(vcpu)) {
 		load_pdptrs(vcpu, vcpu->arch.walk_mmu, kvm_read_cr3(vcpu));
 		mmu_reset_needed = 1;
 	}
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 275b3b646023..e08a12892e8b 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -139,6 +139,11 @@ static inline int is_paging(struct kvm_vcpu *vcpu)
 	return likely(kvm_read_cr0_bits(vcpu, X86_CR0_PG));
 }
 
+static inline bool is_pae_paging(struct kvm_vcpu *vcpu)
+{
+	return !is_long_mode(vcpu) && is_pae(vcpu) && is_paging(vcpu);
+}
+
 static inline u32 bit(int bitno)
 {
 	return 1 << (bitno & 31);
-- 
1.8.3.1

Re: [PATCH] KVM: x86: introduce is_pae_paging

[Sean Christopherson]

On Thu, Jun 06, 2019 at 06:52:52PM +0200, Paolo Bonzini wrote:
> Checking for 32-bit PAE is quite common around code that fiddles with
> the PDPTRs.  Add a function to compress all checks into a single
> invocation.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

I considered adding this helper as well, but shied away because I thought
it might lead to incorrect code, e.g. using is_pae_paging() when is_pae()
is needed.  But, looking at the patch, it's definitely cleaner, so:

Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>