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From: David Edmondson <dme@dme.org>
To: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Cc: Eduardo Habkost <ehabkost@redhat.com>,
	kvm@vger.kernel.org, Michael Roth <michael.roth@amd.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Cameron Esfahani <dirty@apple.com>,
	babu.moger@amd.com, Roman Bolshakov <r.bolshakov@yadro.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [RFC PATCH 8/8] target/i386: Move X86XSaveArea into TCG
Date: Thu, 08 Jul 2021 17:13:57 +0100	[thread overview]
Message-ID: <m235so4wca.fsf@dme.org> (raw)
In-Reply-To: <e4a048f5-cc6d-7bbe-6659-54075cafb9c6@linaro.org>

On Thursday, 2021-07-08 at 08:22:02 -07, Richard Henderson wrote:

> On 7/8/21 12:45 AM, David Edmondson wrote:
>> Actually, that's nonsense. With KVM or HVF we have to use the offsets of
>> the host CPU, as the hardware won't do anything else, irrespective of
>> the general CPU model chosen.
>> 
>> To have KVM -> TCG migration work it would be necessary to pass the
>> offsets in the migration stream and have TCG observe them, as you
>> originally said.
>> 
>> TCG -> KVM migration would only be possible if TCG was configured to use
>> the same offsets as would later required by KVM (meaning, the host CPU).
>
> And kvm -> kvm migration, with the same general cpu model chosen, but with different host 
> cpus with different offsets?
>
> It seems like we must migrate then and verify the offsets in that case, so that we can 
> fail the migration.

Agreed.

I will look into migrating the offsets.

dme.
-- 
The sound of a barking dog on a loop, a plane rises in the crystal blue.

  reply	other threads:[~2021-07-08 16:14 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-05 10:46 [RFC PATCH 0/8] Derive XSAVE state component offsets from CPUID leaf 0xd where possible David Edmondson
2021-07-05 10:46 ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 1/8] target/i386: Declare constants for XSAVE offsets David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 2/8] target/i386: Consolidate the X86XSaveArea offset checks David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 3/8] target/i386: Clarify the padding requirements of X86XSaveArea David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 4/8] target/i386: Pass buffer and length to XSAVE helper David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 5/8] target/i386: Make x86_ext_save_areas visible outside cpu.c David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 6/8] target/i386: Observe XSAVE state area offsets David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 7/8] target/i386: Populate x86_ext_save_areas offsets using cpuid where possible David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-05 10:46 ` [RFC PATCH 8/8] target/i386: Move X86XSaveArea into TCG David Edmondson
2021-07-05 10:46   ` David Edmondson
2021-07-07  1:09   ` Richard Henderson
2021-07-07  1:09     ` Richard Henderson
2021-07-07  6:51     ` Paolo Bonzini
2021-07-07 10:10     ` David Edmondson
2021-07-07 10:10       ` David Edmondson
2021-07-08  7:45       ` David Edmondson
2021-07-08 15:22         ` Richard Henderson
2021-07-08 16:13           ` David Edmondson [this message]
2021-07-05 16:57 ` [RFC PATCH 0/8] Derive XSAVE state component offsets from CPUID leaf 0xd where possible Paolo Bonzini
2021-07-05 16:57   ` Paolo Bonzini

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