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?
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