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Commit 6f550484 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Marcelo Tosatti
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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: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 8b9f4414

arch/x86/kvm/x86.c

+10 −3
Original line number Diff line number Diff line
@@ -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 */