linux-kernel - Re: [PATCH 10/16] KVM: emulate: Handle EGPR index and REX2-incompatible opcodes

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Message-ID: <671a0738-fd16-4bad-bb18-d6367c6c4229@redhat.com>
Date: Mon, 22 Dec 2025 15:36:33 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: "Chang S. Bae" <chang.seok.bae@...el.com>, seanjc@...gle.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, chao.gao@...el.com
Subject: Re: [PATCH 10/16] KVM: emulate: Handle EGPR index and
 REX2-incompatible opcodes

On 12/21/25 05:07, Chang S. Bae wrote:
> @@ -175,6 +175,7 @@
>   #define TwoMemOp    ((u64)1 << 55)  /* Instruction has two memory operand */
>   #define IsBranch    ((u64)1 << 56)  /* Instruction is considered a branch. */
>   #define ShadowStack ((u64)1 << 57)  /* Instruction affects Shadow Stacks. */
> +#define NoRex       ((u64)1 << 58)  /* Instruction has no use of REX prefix */

While you have explained in the commit message that these are 
instructions that ignore REX, the flag is only used for REX2 and you're 
defining it based on the REX2 parts of the manual.

So I would call this NoRex2 ("Instruction not present in REX2 maps").

Paolo