On Fri, Jul 01, 2022 at 12:27:24AM +1200, Kai Huang <kai.huang@xxxxxxxxx> wrote: > On Mon, 2022-06-27 at 14:53 -0700, isaku.yamahata@xxxxxxxxx wrote: > > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > > > TODO: This is a transient workaround patch until the large page support for > > TDX is implemented. Support large page for TDX and remove this patch. > > I don't understand. How does this patch have anything to do with what you are > talking about here? > > If you want to remove this patch later, then why not just explain the reason to > remove when you actually have that patch? > > > > > At this point, large page for TDX isn't supported, and need to allow guest > > TD to work only with 4K pages. On the other hand, conventional VMX VMs > > should continue to work with large page. Allow per-VM override of the TDP > > max page level. > > At which point/previous patch have you made/declared "large page for TDX isn't > supported"? > > If you want to declare you don't want to support large page for TDX, IMHO just > declare it here, for instance: > > "For simplicity, only support 4K page for TD guest." > > > > > In the existing x86 KVM MMU code, there is already max_level member in > > struct kvm_page_fault with KVM_MAX_HUGEPAGE_LEVEL initial value. The KVM > > page fault handler denies page size larger than max_level. > > > > Add per-VM member to indicate the allowed maximum page size with > > KVM_MAX_HUGEPAGE_LEVEL as default value and initialize max_level in struct > > kvm_page_fault with it. For the guest TD, the set per-VM value for allows > > maximum page size to 4K page size. Then only allowed page size is 4K. It > > means large page is disabled. > > To me it's overcomplicated. You just need simple sentences for such simple > infrastructural patch. For instance: > > "TDX requires special handling to support large private page. For simplicity, > only support 4K page for TD guest for now. Add per-VM maximum page level > support to support different maximum page sizes for TD guest and conventional > VMX guest." > > Just for your reference. Thanks for the sentences. I'll replace the commit message with yours. -- Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
