From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
<linux-kernel@vger.kernel.org>, <kvm@vger.kernel.org>
Cc: <kbusch@kernel.org>
Subject: Re: [PATCH 08/10] KVM: x86: Refactor REX prefix handling in instruction emulation
Date: Mon, 17 Nov 2025 11:56:54 -0800 [thread overview]
Message-ID: <dcc0eb50-bb85-486f-aa21-8a06e4a43251@intel.com> (raw)
In-Reply-To: <20251114003633.60689-9-pbonzini@redhat.com>
On 11/13/2025 4:36 PM, Paolo Bonzini wrote:
> From: "Chang S. Bae" <chang.seok.bae@intel.com>
>
> Restructure how to represent and interpret REX fields, preparing
> for handling of both REX2 and VEX.
>
> REX uses the upper four bits of a single byte as a fixed identifier,
> and the lower four bits containing the data. VEX and REX2 extends this so
> that the first byte identifies the prefix and the rest encode additional
> bits; and while VEX only has the same four data bits as REX, eight zero
> bits are a valid value for the data bits of REX2. So, stop storing the
> REX byte as-is. Instead, store only the low bits of the REX prefix and
> track separately whether a REX-like prefix was used.
>
> No functional changes intended.
>
> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
> Message-ID: <20251110180131.28264-11-chang.seok.bae@intel.com>
> [Extracted from APX series; removed bitfields and REX2-specific default. - Paolo]
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Thanks for the incorporation!
next prev parent reply other threads:[~2025-11-17 19:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-14 0:36 [PATCH 00/10] KVM: emulate: enable AVX moves Paolo Bonzini
2025-11-14 0:36 ` [PATCH 01/10] KVM: emulate: add MOVNTDQA Paolo Bonzini
2025-11-14 0:36 ` [PATCH 02/10] KVM: emulate: move Src2Shift up one bit Paolo Bonzini
2025-11-17 19:51 ` Chang S. Bae
2025-11-14 0:36 ` [PATCH 03/10] KVM: emulate: improve formatting of flags table Paolo Bonzini
2025-11-17 19:53 ` Chang S. Bae
2025-11-14 0:36 ` [PATCH 04/10] KVM: emulate: move op_prefix to struct x86_emulate_ctxt Paolo Bonzini
2025-11-17 19:54 ` Chang S. Bae
2025-11-14 0:36 ` [PATCH 05/10] KVM: emulate: share common register decoding code Paolo Bonzini
2025-11-17 19:55 ` Chang S. Bae
2025-11-14 0:36 ` [PATCH 06/10] KVM: emulate: add get_xcr callback Paolo Bonzini
2025-11-17 19:56 ` Chang S. Bae
2025-11-14 0:36 ` [PATCH 07/10] KVM: emulate: add AVX support to register fetch and writeback Paolo Bonzini
2025-11-14 17:06 ` kernel test robot
2025-11-14 20:10 ` kernel test robot
2025-11-14 0:36 ` [PATCH 08/10] KVM: x86: Refactor REX prefix handling in instruction emulation Paolo Bonzini
2025-11-17 19:56 ` Chang S. Bae [this message]
2025-11-14 0:36 ` [PATCH 09/10] KVM: emulate: decode VEX prefix Paolo Bonzini
2025-11-14 0:36 ` [PATCH 10/10] KVM: emulate: enable AVX moves Paolo Bonzini
2025-11-14 0:51 ` [PATCH 00/10] " Keith Busch
2025-11-17 19:57 ` Chang S. Bae
2025-11-21 18:55 ` Sean Christopherson
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