[PATCH 4.19 STABLE] KVM: x86: introduce is_pae_paging - Linux-stable-mirror

11 Nov 2019

From: Paolo Bonzini pbonzini@redhat.com
Upstream commit bf03d4f9334728bf7c8ffc7de787df48abd6340e.
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.
Moving to the common helper also fixes a subtle bug in kvm_set_cr3()
where it fails to check is_long_mode() and results in KVM incorrectly
attempting to load PDPTRs for a 64-bit guest.
Reviewed-by: Sean Christopherson sean.j.christopherson@intel.com
Signed-off-by: Paolo Bonzini pbonzini@redhat.com
[sean: backport to 4.x; handle vmx.c split in 5.x, call out the bugfix]
Signed-off-by: Sean Christopherson sean.j.christopherson@intel.com
---
 arch/x86/kvm/vmx.c | 7 +++----
 arch/x86/kvm/x86.c | 8 ++++----
 arch/x86/kvm/x86.h | 5 +++++
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6f7b3acdab26..83acaed244ba 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5181,7 +5181,7 @@ 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]);
@@ -5193,7 +5193,7 @@ static 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);
@@ -12021,8 +12021,7 @@ 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 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6ae8a013af31..b9b87fb75ac0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -633,7 +633,7 @@ 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,
@@ -884,8 +884,8 @@ 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);
@@ -8312,7 +8312,7 @@ 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 3a91ea760f07..608e5f8c5d0a 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);
-- 
2.24.0


    