From: Xiaoyao Li <xiaoyao.li@intel.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
Marcelo Tosatti <mtosatti@redhat.com>,
Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
Eduardo Habkost <eduardo@habkost.net>,
Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Sergio Lopez <slp@redhat.com>
Subject: Re: [PATCH 0/2] expose host-phys-bits to guest
Date: Thu, 1 Sep 2022 22:36:19 +0800 [thread overview]
Message-ID: <f7a56158-9920-e753-4d21-e1bcc3573e27@intel.com> (raw)
In-Reply-To: <20220901135810.6dicz4grhz7ye2u7@sirius.home.kraxel.org>
On 9/1/2022 9:58 PM, Gerd Hoffmann wrote:
>> Anyway, IMO, guest including guest firmware, should always consult from
>> CPUID leaf 0x80000008 for physical address length.
>
> It simply can't for the reason outlined above. Even if we fix qemu
> today that doesn't solve the problem for the firmware because we want
> backward compatibility with older qemu versions. Thats why I want the
> extra bit which essentially says "CPUID leaf 0x80000008 actually works".
I don't understand how it backward compatible with older qemu version.
Old QEMU won't set the extra bit you introduced in this series, and all
the guest created with old QEMU will become untrusted on CPUID leaf
0x80000008 ?
> take care,
> Gerd
>
next prev parent reply other threads:[~2022-09-01 14:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-31 12:50 [PATCH 0/2] expose host-phys-bits to guest Gerd Hoffmann
2022-08-31 12:50 ` [PATCH 1/2] [hack] reserve bit KVM_HINTS_HOST_PHYS_BITS Gerd Hoffmann
2022-08-31 13:05 ` Michael S. Tsirkin
2022-08-31 12:50 ` [PATCH 2/2] [RfC] expose host-phys-bits to guest Gerd Hoffmann
2022-08-31 12:58 ` Claudio Fontana
2022-09-01 6:07 ` [PATCH 0/2] " Xiaoyao Li
2022-09-01 13:58 ` Gerd Hoffmann
2022-09-01 14:36 ` Xiaoyao Li [this message]
2022-09-01 16:17 ` Gerd Hoffmann
2022-09-02 0:10 ` Xiaoyao Li
2022-09-02 6:07 ` Gerd Hoffmann
2022-09-02 6:35 ` Michael S. Tsirkin
2022-09-02 8:44 ` Gerd Hoffmann
2022-09-04 20:37 ` Michael S. Tsirkin
2022-09-05 7:39 ` Gerd Hoffmann
2022-09-01 14:55 ` Claudio Fontana
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