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Re: [PATCH v2 2/2] kvm: add support for guest physical bits
From: |
Gerd Hoffmann |
Subject: |
Re: [PATCH v2 2/2] kvm: add support for guest physical bits |
Date: |
Wed, 13 Mar 2024 09:15:38 +0100 |
On Wed, Mar 13, 2024 at 02:39:32PM +0800, Tao Su wrote:
> On Tue, Mar 05, 2024 at 11:52:33AM +0100, Gerd Hoffmann wrote:
> > Query kvm for supported guest physical address bits, in cpuid
> > function 80000008, eax[23:16]. Usually this is identical to host
> > physical address bits. With NPT or EPT being used this might be
> > restricted to 48 (max 4-level paging address space size) even if
> > the host cpu supports more physical address bits.
> >
> > When set pass this to the guest, using cpuid too. Guest firmware
> > can use this to figure how big the usable guest physical address
> > space is, so PCI bar mapping are actually reachable.
>
> If this patch is applied, do you have plans to implement it in
> OVMF/Seabios?
Yes. ovmf test patches:
https://github.com/kraxel/edk2/commits/devel/guest-phys-bits/
take care,
Gerd