Messages in this thread Patch in this message |  | | Date | Wed, 6 May 2026 14:12:04 -0700 | | Subject | Re: [PATCH] KVM: x86: Swap the dst and src operand for MOVNTDQA | | From | Sean Christopherson <> |
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On Wed, May 06, 2026, Sean Christopherson wrote: > Swap the MOVNTDQA operands, as MOVNTDQA does NOT in fact have "the same > characteristics as 0F E7 (MOVNTDQ)"; MOVNTDQA loads from memory and stores > to registers, while MOVNTDQ loads from registers and stores to memory. > > Per the SDM: > > MOVNTDQ - Move packed integer values in xmm1 to m128 using non-temporal > hint. > > MOVNTDQA - Move double quadword from m128 to xmm1 using non-temporal hint > if WC memory type. > > Reported-by: Josh Eads <josheads@google.com> > Fixes: c57d9bafbd0b ("KVM: x86: Add support for emulating MOVNTDQA") > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > > I have updates to the xsave KUT test to verify the bug and the fix. > > arch/x86/kvm/emulate.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index c8c6cc0406d6..0bb832a76868 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -4450,7 +4450,7 @@ static const struct opcode twobyte_table[256] = { > /* 0xD0 - 0xDF */ > N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, > /* 0xE0 - 0xEF */ > - N, N, N, N, N, N, N, GP(SrcReg | DstMem | ModRM | Mov, &pfx_0f_e7_0f_38_2a), > + N, N, N, N, N, N, N, GP(SrcMem | DstReg | ModRM | Mov, &pfx_0f_e7_0f_38_2a),
Aaaaand Josh pointed out that I wasn't paying attention and stomped all over MOVNTDQ. I'll figure out why my KUT changes didn't detect this, and send a v2.
> N, N, N, N, N, N, N, N, > /* 0xF0 - 0xFF */ > N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N > @@ -4481,7 +4481,7 @@ static const struct opcode opcode_map_0f_38[256] = { > X16(N), X16(N), > /* 0x20 - 0x2f */ > X8(N), > - X2(N), GP(SrcReg | DstMem | ModRM | Mov | Aligned, &pfx_0f_e7_0f_38_2a), N, N, N, N, N, > + X2(N), GP(SrcMem | DstReg | ModRM | Mov | Aligned, &pfx_0f_e7_0f_38_2a), N, N, N, N, N, > /* 0x30 - 0x7f */ > X16(N), X16(N), X16(N), X16(N), X16(N), > /* 0x80 - 0xef */ > > base-commit: 6d35786de28116ecf78797a62b84e6bf3c45aa5a > -- > 2.54.0.545.g6539524ca2-goog >
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