[PATCH 5.7 217/265] KVM: nVMX: Plumb L2 GPA through to PML emulation

Sasha Levin
2020-06-29T18:35:33Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

commit 2dbebf7ae1ed9a420d954305e2c9d5ed39ec57c3 upstream.

Explicitly pass the L2 GPA to kvm_arch_write_log_dirty(), which for all
intents and purposes is vmx_write_pml_buffer(), instead of having the
latter pull the GPA from vmcs.GUEST_PHYSICAL_ADDRESS. If the dirty bit
update is the result of KVM emulation (rare for L2), then the GPA in the
VMCS may be stale and/or hold a completely unrelated GPA.

Fixes: c5f983f6e8455 ("nVMX: Implement emulated Page Modification Logging")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200622215832.22090-2-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/mmu.h | 2 +-
arch/x86/kvm/mmu/mmu.c | 4 ++--
arch/x86/kvm/mmu/paging_tmpl.h | 7 ++++---
arch/x86/kvm/vmx/vmx.c | 6 +++---
5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0a6b35353fc79..86e2e0272c576 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1195,7 +1195,7 @@ struct kvm_x86_ops {
void (*enable_log_dirty_pt_masked)(struct kvm *kvm,
struct kvm_memory_slot *slot,
gfn_t offset, unsigned long mask);
- int (*write_log_dirty)(struct kvm_vcpu *vcpu);
+ int (*write_log_dirty)(struct kvm_vcpu *vcpu, gpa_t l2_gpa);

/* pmu operations of sub-arch */
const struct kvm_pmu_ops *pmu_ops;
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 8a3b1bce722a4..d0e3b1b6845b5 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -222,7 +222,7 @@ void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn);
bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
struct kvm_memory_slot *slot, u64 gfn);
-int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu);
+int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu, gpa_t l2_gpa);

int kvm_mmu_post_init_vm(struct kvm *kvm);
void kvm_mmu_pre_destroy_vm(struct kvm *kvm);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 92d0569541943..eb27ab47d6073 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1746,10 +1746,10 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
* Emulate arch specific page modification logging for the
* nested hypervisor
*/
-int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu)
+int kvm_arch_write_log_dirty(struct kvm_vcpu *vcpu, gpa_t l2_gpa)
{
if (kvm_x86_ops.write_log_dirty)
- return kvm_x86_ops.write_log_dirty(vcpu);
+ return kvm_x86_ops.write_log_dirty(vcpu, l2_gpa);

return 0;
}
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 9bdf9b7d9a962..7098f843eabdd 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -235,7 +235,7 @@ static inline unsigned FNAME(gpte_access)(u64 gpte)
static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu,
struct kvm_mmu *mmu,
struct guest_walker *walker,
- int write_fault)
+ gpa_t addr, int write_fault)
{
unsigned level, index;
pt_element_t pte, orig_pte;
@@ -260,7 +260,7 @@ static int FNAME(update_accessed_dirty_bits)(struct kvm_vcpu *vcpu,
!(pte & PT_GUEST_DIRTY_MASK)) {
trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte));
#if PTTYPE == PTTYPE_EPT
- if (kvm_arch_write_log_dirty(vcpu))
+ if (kvm_arch_write_log_dirty(vcpu, addr))
return -EINVAL;
#endif
pte |= PT_GUEST_DIRTY_MASK;
@@ -457,7 +457,8 @@ retry_walk:
(PT_GUEST_DIRTY_SHIFT - PT_GUEST_ACCESSED_SHIFT);

if (unlikely(!accessed_dirty)) {
- ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker, write_fault);
+ ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker,
+ addr, write_fault);
if (unlikely(ret < 0))
goto error;
else if (ret)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 8f59f8c8fd05d..2d7ce012b1d5f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7333,11 +7333,11 @@ static void vmx_flush_log_dirty(struct kvm *kvm)
kvm_flush_pml_buffers(kvm);
}

-static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
+static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu, gpa_t gpa)
{
struct vmcs12 *vmcs12;
struct vcpu_vmx *vmx = to_vmx(vcpu);
- gpa_t gpa, dst;
+ gpa_t dst;

if (is_guest_mode(vcpu)) {
WARN_ON_ONCE(vmx->nested.pml_full);
@@ -7356,7 +7356,7 @@ static int vmx_write_pml_buffer(struct kvm_vcpu *vcpu)
return 1;
}

- gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS) & ~0xFFFull;
+ gpa &= ~0xFFFull;
dst = vmcs12->pml_address + sizeof(u64) * vmcs12->guest_pml_index;

if (kvm_write_guest_page(vcpu->kvm, gpa_to_gfn(dst), &gpa,
--
2.25.1