On 22/03/2018 10:07, Paolo Bonzini wrote:
> On 22/03/2018 09:34, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>>
>> Explicit segment overides other than %fs and %gs are documented as ignored by
>> both Intel and AMD.
>>
>> In practice, this means that:
>>
>> * Explicit uses of %ss don't actually yield #SS[0] for non-canonical
>> memory references.
>> * Explicit uses of %{e,c,d}s don't override %rbp/%rsp-based memory references
>> to yield #GP[0] for non-canonical memory references.
>>
>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
When porting fixes from other projects, it is customary to identify so
in the commit message. In this case, the fix you've ported is
http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=b7dce29d9faf3597d009c853ed1fcbed9f7a7f68
Here is an example of how Xen ports fixes from Linux for the drivers
that we share.
http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=4e131596f1defec9407b6e60d584a696beaf5d7e
>> ---
>> arch/x86/kvm/emulate.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
>> index dd88158..5091255 100644
>> --- a/arch/x86/kvm/emulate.c
>> +++ b/arch/x86/kvm/emulate.c
>> @@ -5148,8 +5148,10 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
>> case 0x2e: /* CS override */
>> case 0x36: /* SS override */
>> case 0x3e: /* DS override */
>> - has_seg_override = true;
>> - ctxt->seg_override = (ctxt->b >> 3) & 3;
>> + if (mode != X86EMUL_MODE_PROT64) {
>> + has_seg_override = true;
>> + ctxt->seg_override = (ctxt->b >> 3) & 3;
>> + }
>> break;
>> case 0x64: /* FS override */
>> case 0x65: /* GS override */
>>
> Testcase, please...
If you want to crib from one, this is the testcase I made for Xen.
http://xenbits.xen.org/docs/xtf/test-memop-seg.html
With the impending KVM/PVH work which is ongoing, it will soon be easy
to run Xen's HVM test suite unmodified under KVM, but we're not quite
there yet.
~Andrew
