KVM: x86 emulator: fix memory access during x86 emulation

Currently when x86 emulator needs to access memory, page walk is done with
broadest permission possible, so if emulated instruction was executed
by userspace process it can still access kernel memory. Fix that by
providing correct memory access to page walker during emulation.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 18 insertions, 3 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 784d7c586d8e..7a6f54fa13ba 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -54,13 +54,23 @@ struct x86_emulate_ctxt;
 struct x86_emulate_ops {
         /*
          * read_std: Read bytes of standard (non-emulated/special) memory.
-         *           Used for instruction fetch, stack operations, and others.
+         *           Used for descriptor reading.
          *  @addr:  [IN ] Linear address from which to read.
          *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
          *  @bytes: [IN ] Number of bytes to read from memory.
          */
         int (*read_std)(unsigned long addr, void *val,
-                        unsigned int bytes, struct kvm_vcpu *vcpu);
+                        unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
+
+        /*
+         * fetch: Read bytes of standard (non-emulated/special) memory.
+         *        Used for instruction fetch.
+         *  @addr:  [IN ] Linear address from which to read.
+         *  @val:   [OUT] Value read from memory, zero-extended to 'u_long'.
+         *  @bytes: [IN ] Number of bytes to read from memory.
+         */
+        int (*fetch)(unsigned long addr, void *val,
+                        unsigned int bytes, struct kvm_vcpu *vcpu, u32 *error);
 
         /*
          * read_emulated: Read bytes from emulated/special memory area.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 152233723844..c07c16f64015 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -243,7 +243,8 @@ struct kvm_mmu {
         void (*new_cr3)(struct kvm_vcpu *vcpu);
         int (*page_fault)(struct kvm_vcpu *vcpu, gva_t gva, u32 err);
         void (*free)(struct kvm_vcpu *vcpu);
-        gpa_t (*gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t gva);
+        gpa_t (*gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t gva, u32 access,
+                            u32 *error);
         void (*prefetch_page)(struct kvm_vcpu *vcpu,
                               struct kvm_mmu_page *page);
         int (*sync_page)(struct kvm_vcpu *vcpu,
@@ -660,6 +661,10 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
 int kvm_mmu_load(struct kvm_vcpu *vcpu);
 void kvm_mmu_unload(struct kvm_vcpu *vcpu);
 void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu);
+gpa_t kvm_mmu_gva_to_gpa_read(struct kvm_vcpu *vcpu, gva_t gva, u32 *error);
+gpa_t kvm_mmu_gva_to_gpa_fetch(struct kvm_vcpu *vcpu, gva_t gva, u32 *error);
+gpa_t kvm_mmu_gva_to_gpa_write(struct kvm_vcpu *vcpu, gva_t gva, u32 *error);
+gpa_t kvm_mmu_gva_to_gpa_system(struct kvm_vcpu *vcpu, gva_t gva, u32 *error);
 
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);