From: Jan Kiszka <jan.kiszka@siemens.com>
To: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>,
qemu-devel <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>,
Christophe Fergeau <cfergeau@redhat.com>
Subject: Re: [PATCH][uq/master] kvm: x86: Save/restore FPU OP, IP and DP
Date: Wed, 15 Jun 2011 13:45:36 +0200 [thread overview]
Message-ID: <4DF89B60.10606@siemens.com> (raw)
In-Reply-To: <4DF8988C.7010401@redhat.com>
On 2011-06-15 13:33, Avi Kivity wrote:
> On 06/15/2011 02:32 PM, Jan Kiszka wrote:
>>>
>>> If it isn't zero, there's still a good chance fopcode will be zero
>>> (64-bit userspace, thread that hasn't used the fpu since the last
>>> context switch, last opcode happened to be zero).
>>
>> I do not yet find "if fopcode is invalid, it is zero, just as IP and DP"
>> in the spec. What clears them reliably?
>
> FNINIT
OK, I see. So we simply check for all fields being zero and skip the
section in that case. The MSR doesn't actually to us here.
Will write v2.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
WARNING: multiple messages have this Message-ID (diff)
From: Jan Kiszka <jan.kiszka@siemens.com>
To: Avi Kivity <avi@redhat.com>
Cc: Christophe Fergeau <cfergeau@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Subject: Re: [Qemu-devel] [PATCH][uq/master] kvm: x86: Save/restore FPU OP, IP and DP
Date: Wed, 15 Jun 2011 13:45:36 +0200 [thread overview]
Message-ID: <4DF89B60.10606@siemens.com> (raw)
In-Reply-To: <4DF8988C.7010401@redhat.com>
On 2011-06-15 13:33, Avi Kivity wrote:
> On 06/15/2011 02:32 PM, Jan Kiszka wrote:
>>>
>>> If it isn't zero, there's still a good chance fopcode will be zero
>>> (64-bit userspace, thread that hasn't used the fpu since the last
>>> context switch, last opcode happened to be zero).
>>
>> I do not yet find "if fopcode is invalid, it is zero, just as IP and DP"
>> in the spec. What clears them reliably?
>
> FNINIT
OK, I see. So we simply check for all fields being zero and skip the
section in that case. The MSR doesn't actually to us here.
Will write v2.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2011-06-15 11:45 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-11 9:23 [PATCH][uq/master] kvm: x86: Save/restore FPU OP, IP and DP Jan Kiszka
2011-06-11 9:23 ` [Qemu-devel] " Jan Kiszka
2011-06-13 8:45 ` Avi Kivity
2011-06-13 8:45 ` [Qemu-devel] " Avi Kivity
2011-06-14 6:10 ` Jan Kiszka
2011-06-14 6:10 ` [Qemu-devel] " Jan Kiszka
2011-06-14 8:23 ` Avi Kivity
2011-06-14 8:23 ` [Qemu-devel] " Avi Kivity
2011-06-14 8:28 ` Jan Kiszka
2011-06-14 8:28 ` [Qemu-devel] " Jan Kiszka
2011-06-15 9:10 ` Avi Kivity
2011-06-15 9:10 ` [Qemu-devel] " Avi Kivity
2011-06-15 10:20 ` Jan Kiszka
2011-06-15 10:20 ` [Qemu-devel] " Jan Kiszka
2011-06-15 10:39 ` Jan Kiszka
2011-06-15 10:39 ` [Qemu-devel] " Jan Kiszka
2011-06-15 11:26 ` Avi Kivity
2011-06-15 11:26 ` [Qemu-devel] " Avi Kivity
2011-06-15 11:32 ` Jan Kiszka
2011-06-15 11:32 ` [Qemu-devel] " Jan Kiszka
2011-06-15 11:33 ` Avi Kivity
2011-06-15 11:33 ` [Qemu-devel] " Avi Kivity
2011-06-15 11:45 ` Jan Kiszka [this message]
2011-06-15 11:45 ` Jan Kiszka
2011-06-15 13:17 ` [PATCH v2][uq/master] " Jan Kiszka
2011-06-15 13:17 ` [Qemu-devel] " Jan Kiszka
2011-06-16 9:42 ` Christophe Fergeau
2011-06-16 9:42 ` Christophe Fergeau
2011-06-19 12:58 ` Avi Kivity
2011-06-19 12:58 ` [Qemu-devel] " Avi Kivity
2011-06-16 9:35 ` [PATCH][uq/master] " Christophe Fergeau
2011-06-16 9:35 ` [Qemu-devel] " Christophe Fergeau
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