KVM: Fix load_guest_segment_descriptor() to inject page fault

This patch injects page fault when reading descriptor in
load_guest_segment_descriptor() fails with FAULT.

Effects of this injection: This function is used by
kvm_load_segment_descriptor() which is necessary for the
following instructions:

 - mov seg,r/m16
 - jmp far
 - pop ?s

This patch makes it possible to emulate the page faults
generated by these instructions. But be sure that unless
we change the kvm_load_segment_descriptor()'s ret value
propagation this patch has no effect.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f6ae4875d9d..203ee7d0ed5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4713,6 +4713,9 @@ static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
 {
         struct descriptor_table dtable;
         u16 index = selector >> 3;
+        int ret;
+        u32 err;
+        gva_t addr;
 
         get_segment_descriptor_dtable(vcpu, selector, &dtable);
 
@@ -4720,9 +4723,13 @@ static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
                 kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
                 return X86EMUL_PROPAGATE_FAULT;
         }
-        return kvm_read_guest_virt_system(dtable.base + index*8,
-                                          seg_desc, sizeof(*seg_desc),
-                                          vcpu, NULL);
+        addr = dtable.base + index * 8;
+        ret = kvm_read_guest_virt_system(addr, seg_desc, sizeof(*seg_desc),
+                                         vcpu,  &err);
+        if (ret == X86EMUL_PROPAGATE_FAULT)
+                kvm_inject_page_fault(vcpu, addr, err);
+
+       return ret;
 }
 
 /* allowed just for 8 bytes segments */