From: Richard Henderson <rth@twiddle.net>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
qemu-devel@nongnu.org, Huaitong Han <huaitong.han@intel.com>,
kvm@vger.kernel.org
Subject: Re: [Qemu-devel] [for-2.6 PATCH 1/3] target-i386: Define structs for layout of xsave area
Date: Tue, 1 Dec 2015 09:20:41 -0800 [thread overview]
Message-ID: <565DD6E9.1040906@twiddle.net> (raw)
In-Reply-To: <20151201171550.GN23717@thinpad.lan.raisama.net>
On 12/01/2015 09:15 AM, Eduardo Habkost wrote:
> On Tue, Dec 01, 2015 at 09:09:47AM -0800, Richard Henderson wrote:
>> On 11/30/2015 03:18 AM, Paolo Bonzini wrote:
>>> Because this is always little endian, I would write it as uint8_t[16][16].
>>
>> Maybe. That isn't altogether handy for TCG, since we'll be wanting to bswap
>> these buffers (probably in uint64_t chunks).
>
> X86XSaveArea will be used only when loading/saving state using
> xsave, not for executing regular instructions.
... like the regular instruction xsave?
https://patchwork.ozlabs.org/patch/493318/
> In X86CPU, the
> data is already stored as XMMReg unions (the one with the
> XMM_[BWDQ] helpers).
Of course. But those unions are arranged to be in big-endian format on
big-endian hosts. So we need to swap the data back to little-endian format for
storage into guest memory.
r~
WARNING: multiple messages have this Message-ID (diff)
From: Richard Henderson <rth@twiddle.net>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
Huaitong Han <huaitong.han@intel.com>
Subject: Re: [Qemu-devel] [for-2.6 PATCH 1/3] target-i386: Define structs for layout of xsave area
Date: Tue, 1 Dec 2015 09:20:41 -0800 [thread overview]
Message-ID: <565DD6E9.1040906@twiddle.net> (raw)
In-Reply-To: <20151201171550.GN23717@thinpad.lan.raisama.net>
On 12/01/2015 09:15 AM, Eduardo Habkost wrote:
> On Tue, Dec 01, 2015 at 09:09:47AM -0800, Richard Henderson wrote:
>> On 11/30/2015 03:18 AM, Paolo Bonzini wrote:
>>> Because this is always little endian, I would write it as uint8_t[16][16].
>>
>> Maybe. That isn't altogether handy for TCG, since we'll be wanting to bswap
>> these buffers (probably in uint64_t chunks).
>
> X86XSaveArea will be used only when loading/saving state using
> xsave, not for executing regular instructions.
... like the regular instruction xsave?
https://patchwork.ozlabs.org/patch/493318/
> In X86CPU, the
> data is already stored as XMMReg unions (the one with the
> XMM_[BWDQ] helpers).
Of course. But those unions are arranged to be in big-endian format on
big-endian hosts. So we need to swap the data back to little-endian format for
storage into guest memory.
r~
next prev parent reply other threads:[~2015-12-01 17:20 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-28 19:56 [for-2.6 PATCH 0/3] target-i386: Use C struct for xsave area layout, offsets & sizes Eduardo Habkost
2015-11-28 19:56 ` [Qemu-devel] " Eduardo Habkost
2015-11-28 19:56 ` [for-2.6 PATCH 1/3] target-i386: Define structs for layout of xsave area Eduardo Habkost
2015-11-28 19:56 ` [Qemu-devel] " Eduardo Habkost
2015-11-30 11:18 ` Paolo Bonzini
2015-11-30 11:18 ` [Qemu-devel] " Paolo Bonzini
2015-11-30 14:48 ` Eduardo Habkost
2015-11-30 14:48 ` [Qemu-devel] " Eduardo Habkost
2015-12-01 17:09 ` Richard Henderson
2015-12-01 17:15 ` Eduardo Habkost
2015-12-01 17:15 ` Eduardo Habkost
2015-12-01 17:20 ` Richard Henderson [this message]
2015-12-01 17:20 ` Richard Henderson
2015-12-01 17:27 ` Paolo Bonzini
2015-12-01 17:27 ` Paolo Bonzini
2015-12-01 18:34 ` Eduardo Habkost
2015-12-01 18:34 ` Eduardo Habkost
2015-12-01 18:42 ` Richard Henderson
2015-12-01 18:42 ` Richard Henderson
2015-11-28 19:56 ` [for-2.6 PATCH 2/3] target-i386: Use xsave structs for ext_save_area Eduardo Habkost
2015-11-28 19:56 ` [Qemu-devel] " Eduardo Habkost
2015-11-28 19:56 ` [for-2.6 PATCH 3/3] target-i386: kvm: Use X86XSaveArea struct for xsave save/load Eduardo Habkost
2015-11-28 19:56 ` [Qemu-devel] " Eduardo Habkost
2015-11-30 11:21 ` [for-2.6 PATCH 0/3] target-i386: Use C struct for xsave area layout, offsets & sizes Paolo Bonzini
2015-11-30 11:21 ` [Qemu-devel] " Paolo Bonzini
2015-11-30 14:14 ` Eduardo Habkost
2015-11-30 14:14 ` [Qemu-devel] " Eduardo Habkost
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