Re: [PATCH v6 07/16] KVM: MMU: Introduce level info in PFERR code

Isaku Yamahata
2023-11-21T10:02:48Z

On Mon, Nov 20, 2023 at 06:54:07PM +0800,
Binbin Wu <binbin.wu@linux.intel.com> wrote:

>
>
> On 11/7/2023 11:00 PM, isaku.yamahata@intel.com wrote:
> > From: Xiaoyao Li <xiaoyao.li@intel.com>
> >
> > For TDX, EPT violation can happen when TDG.MEM.PAGE.ACCEPT.
> > And TDG.MEM.PAGE.ACCEPT contains the desired accept page level of TD guest.
> >
> > 1. KVM can map it with 4KB page while TD guest wants to accept 2MB page.
> >
> > TD geust will get TDX_PAGE_SIZE_MISMATCH and it should try to accept
> s/geust/guest
>
> > 4KB size.
> >
> > 2. KVM can map it with 2MB page while TD guest wants to accept 4KB page.
> >
> > KVM needs to honor it because
> > a) there is no way to tell guest KVM maps it as 2MB size. And
> > b) guest accepts it in 4KB size since guest knows some other 4KB page
> > in the same 2MB range will be used as shared page.
> >
> > For case 2, it need to pass desired page level to MMU's
> > page_fault_handler. Use bit 29:31 of kvm PF error code for this purpose.
>
> The level info is needed not only for case 2, KVM also needs the info so
> that
> it can map a 2MB page when TD guest wants to accept a 2MB page.

"MMU's page_fault_handler" = KVM MMU page fault handler, isn't it?
I'll replace it with KVM MMU page fault handler for clarity.
--
Isaku Yamahata <isaku.yamahata@linux.intel.com>