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Subject[PATCH 17/27] KVM: MMU: Track page fault data in struct vcpu
Date
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>
---
arch/x86/include/asm/kvm_emulate.h | 1 -
arch/x86/include/asm/kvm_host.h | 9 +++++++++
arch/x86/kvm/emulate.c | 30 ++++++++++++++----------------
arch/x86/kvm/paging_tmpl.h | 4 ++++
arch/x86/kvm/x86.c | 3 ++-
5 files changed, 29 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 1bf1140..5187dd8 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 a338235..e5eb57c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -313,6 +313,15 @@ struct kvm_vcpu_arch {
*/
struct kvm_mmu *walk_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;
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 27d2c22..2b08b78 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/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index a5b5759..20fc815 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -273,6 +273,10 @@ 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;
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b2fe9e7..38d482d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4130,7 +4130,8 @@ 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, vcpu->arch.fault.address,
+ vcpu->arch.fault.error_code);
else if (ctxt->error_code_valid)
kvm_queue_exception_e(vcpu, ctxt->exception, ctxt->error_code);
else
--
1.7.0.4



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