KVM: MMU: Track page fault data in struct vcpu

This patch introduces a struct with two new fields in
vcpu_arch for x86:

	* fault.address
	* fault.error_code

This will be used to correctly propagate page faults back
into the guest when we could have either an ordinary page
fault or a nested page fault. In the case of a nested page
fault the fault-address is different from the original
address that should be walked. So we need to keep track
about the real fault-address.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

6 files changed, 38 insertions, 31 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 1bf11400ae9..5187dd88019 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -229,7 +229,6 @@ struct x86_emulate_ctxt {
         int exception; /* exception that happens during emulation or -1 */
         u32 error_code; /* error code for exception */
         bool error_code_valid;
-        unsigned long cr2; /* faulted address in case of #PF */
 
         /* decode cache */
         struct decode_cache decode;
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 009a4a1b370..3fde5b32253 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -239,9 +239,7 @@ struct kvm_mmu {
         void (*set_cr3)(struct kvm_vcpu *vcpu, unsigned long root);
         unsigned long (*get_cr3)(struct kvm_vcpu *vcpu);
         int (*page_fault)(struct kvm_vcpu *vcpu, gva_t gva, u32 err);
-        void (*inject_page_fault)(struct kvm_vcpu *vcpu,
-                                  unsigned long addr,
-                                  u32 error_code);
+        void (*inject_page_fault)(struct kvm_vcpu *vcpu);
         void (*free)(struct kvm_vcpu *vcpu);
         gpa_t (*gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t gva, u32 access,
                             u32 *error);
@@ -288,6 +286,16 @@ struct kvm_vcpu_arch {
         bool tpr_access_reporting;
 
         struct kvm_mmu mmu;
+
+        /*
+         * This struct is filled with the necessary information to propagate a
+         * page fault into the guest
+         */
+        struct {
+                u64      address;
+                unsigned error_code;
+        } fault;
+
         /* only needed in kvm_pv_mmu_op() path, but it's hot so
          * put it here to avoid allocation */
         struct kvm_pv_mmu_op_buffer mmu_op_buffer;
@@ -624,8 +632,7 @@ void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
 void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
 void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
 void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
-void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long cr2,
-                           u32 error_code);
+void kvm_inject_page_fault(struct kvm_vcpu *vcpu);
 bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
 
 int kvm_pic_set_irq(void *opaque, int irq, int level);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 27d2c22b114..2b08b78b6ca 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -487,11 +487,9 @@ static void emulate_gp(struct x86_emulate_ctxt *ctxt, int err)
         emulate_exception(ctxt, GP_VECTOR, err, true);
 }
 
-static void emulate_pf(struct x86_emulate_ctxt *ctxt, unsigned long addr,
-                       int err)
+static void emulate_pf(struct x86_emulate_ctxt *ctxt)
 {
-        ctxt->cr2 = addr;
-        emulate_exception(ctxt, PF_VECTOR, err, true);
+        emulate_exception(ctxt, PF_VECTOR, 0, true);
 }
 
 static void emulate_ud(struct x86_emulate_ctxt *ctxt)
@@ -834,7 +832,7 @@ static int read_emulated(struct x86_emulate_ctxt *ctxt,
                 rc = ops->read_emulated(addr, mc->data + mc->end, n, &err,
                                         ctxt->vcpu);
                 if (rc == X86EMUL_PROPAGATE_FAULT)
-                        emulate_pf(ctxt, addr, err);
+                        emulate_pf(ctxt);
                 if (rc != X86EMUL_CONTINUE)
                         return rc;
                 mc->end += n;
@@ -921,7 +919,7 @@ static int read_segment_descriptor(struct x86_emulate_ctxt *ctxt,
         addr = dt.address + index * 8;
         ret = ops->read_std(addr, desc, sizeof *desc, ctxt->vcpu,  &err);
         if (ret == X86EMUL_PROPAGATE_FAULT)
-                emulate_pf(ctxt, addr, err);
+                emulate_pf(ctxt);
 
        return ret;
 }
@@ -947,7 +945,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
         addr = dt.address + index * 8;
         ret = ops->write_std(addr, desc, sizeof *desc, ctxt->vcpu, &err);
         if (ret == X86EMUL_PROPAGATE_FAULT)
-                emulate_pf(ctxt, addr, err);
+                emulate_pf(ctxt);
 
         return ret;
 }
@@ -1117,7 +1115,7 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
                                         &err,
                                         ctxt->vcpu);
                 if (rc == X86EMUL_PROPAGATE_FAULT)
-                        emulate_pf(ctxt, c->dst.addr.mem, err);
+                        emulate_pf(ctxt);
                 if (rc != X86EMUL_CONTINUE)
                         return rc;
                 break;
@@ -1939,7 +1937,7 @@ static int task_switch_16(struct x86_emulate_ctxt *ctxt,
                             &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, old_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -1949,7 +1947,7 @@ static int task_switch_16(struct x86_emulate_ctxt *ctxt,
                              &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, old_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -1957,7 +1955,7 @@ static int task_switch_16(struct x86_emulate_ctxt *ctxt,
                             &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, new_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -1970,7 +1968,7 @@ static int task_switch_16(struct x86_emulate_ctxt *ctxt,
                                      ctxt->vcpu, &err);
                 if (ret == X86EMUL_PROPAGATE_FAULT) {
                         /* FIXME: need to provide precise fault address */
-                        emulate_pf(ctxt, new_tss_base, err);
+                        emulate_pf(ctxt);
                         return ret;
                 }
         }
@@ -2081,7 +2079,7 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt,
                             &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, old_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -2091,7 +2089,7 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt,
                              &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, old_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -2099,7 +2097,7 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt,
                             &err);
         if (ret == X86EMUL_PROPAGATE_FAULT) {
                 /* FIXME: need to provide precise fault address */
-                emulate_pf(ctxt, new_tss_base, err);
+                emulate_pf(ctxt);
                 return ret;
         }
 
@@ -2112,7 +2110,7 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt,
                                      ctxt->vcpu, &err);
                 if (ret == X86EMUL_PROPAGATE_FAULT) {
                         /* FIXME: need to provide precise fault address */
-                        emulate_pf(ctxt, new_tss_base, err);
+                        emulate_pf(ctxt);
                         return ret;
                 }
         }
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 86f7557cf3f..99367274b97 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2566,11 +2566,9 @@ static unsigned long get_cr3(struct kvm_vcpu *vcpu)
         return vcpu->arch.cr3;
 }
 
-static void inject_page_fault(struct kvm_vcpu *vcpu,
-                              u64 addr,
-                              u32 err_code)
+static void inject_page_fault(struct kvm_vcpu *vcpu)
 {
-        vcpu->arch.mmu.inject_page_fault(vcpu, addr, err_code);
+        vcpu->arch.mmu.inject_page_fault(vcpu);
 }
 
 static void paging_free(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 68ee1b7fa89..d07f48a06f0 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -258,6 +258,10 @@ error:
                 walker->error_code |= PFERR_FETCH_MASK;
         if (rsvd_fault)
                 walker->error_code |= PFERR_RSVD_MASK;
+
+        vcpu->arch.fault.address    = addr;
+        vcpu->arch.fault.error_code = walker->error_code;
+
         trace_kvm_mmu_walker_error(walker->error_code);
         return 0;
 }
@@ -521,7 +525,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
          */
         if (!r) {
                 pgprintk("%s: guest page fault\n", __func__);
-                inject_page_fault(vcpu, addr, walker.error_code);
+                inject_page_fault(vcpu);
                 vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
                 return 0;
         }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9d434777154..48b74d2fbfb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -329,11 +329,12 @@ void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr)
 }
 EXPORT_SYMBOL_GPL(kvm_requeue_exception);
 
-void kvm_inject_page_fault(struct kvm_vcpu *vcpu, unsigned long addr,
-                           u32 error_code)
+void kvm_inject_page_fault(struct kvm_vcpu *vcpu)
 {
+        unsigned error_code = vcpu->arch.fault.error_code;
+
         ++vcpu->stat.pf_guest;
-        vcpu->arch.cr2 = addr;
+        vcpu->arch.cr2 = vcpu->arch.fault.address;
         kvm_queue_exception_e(vcpu, PF_VECTOR, error_code);
 }
 
@@ -4080,7 +4081,7 @@ static void inject_emulated_exception(struct kvm_vcpu *vcpu)
 {
         struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;
         if (ctxt->exception == PF_VECTOR)
-                kvm_inject_page_fault(vcpu, ctxt->cr2, ctxt->error_code);
+                kvm_inject_page_fault(vcpu);
         else if (ctxt->error_code_valid)
                 kvm_queue_exception_e(vcpu, ctxt->exception, ctxt->error_code);
         else