Sorry for being late to reply.
Japan was a holiday yesterday.
Avi Kivity wrote:
On 02/10/2010 03:50 AM, Takuya Yoshikawa wrote:
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.
@@ -4655,6 +4655,7 @@ static int load_guest_segment_descriptor(struct
kvm_vcpu *vcpu, u16 selector,
{
struct descriptor_table dtable;
u16 index = selector>> 3;
+ int ret;
get_segment_descriptor_dtable(vcpu, selector,&dtable);
@@ -4662,7 +4663,11 @@ 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(dtable.base + index*8, seg_desc,
sizeof(*seg_desc), vcpu);
+ ret = kvm_read_guest_virt(dtable.base + index*8, seg_desc,
sizeof(*seg_desc), vcpu);
+ if (ret == X86EMUL_PROPAGATE_FAULT)
+ kvm_inject_page_fault(vcpu, dtable.base + index*8, 0);
+
+ return ret;
}
If the descriptor table is not aligned, and a descriptor spans two
pages, then we might need to inject a page fault at some other address.
Also, the injection should be done in kvm_read_guest_virt() to avoid
duplicating code.
These instructions however are only emulated in big real mode. Where
did you encounter the need to inject page faults during their emulation?
I did not notice about that, we need not inject page faults for them.
But as Marcelo says in the next mail ...
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