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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Josh Eads <josheads@google.com>
Subject: [PATCH] KVM: x86: Swap the dst and src operand for MOVNTDQA
Date: Wed,  6 May 2026 11:55:10 -0700	[thread overview]
Message-ID: <20260506185510.2723091-1-seanjc@google.com> (raw)

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),
 	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


             reply	other threads:[~2026-05-06 18:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-06 18:55 Sean Christopherson [this message]
2026-05-06 21:12 ` [PATCH] KVM: x86: Swap the dst and src operand for MOVNTDQA Sean Christopherson
2026-05-06 21:32   ` Sean Christopherson

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