On Sat, Apr 22, 2023, Zhi Wang wrote:
> On Sun, 12 Mar 2023 10:56:12 -0700
> isaku.yamahata@xxxxxxxxx wrote:
>
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> >
> > TDX doesn't support dirty logging. Report dirty logging isn't supported so
> > that device model, for example qemu, can properly handle it. Silently
> > ignore on dirty logging on private GFNs of TDX.
...
> > +bool kvm_arch_dirty_log_supported(struct kvm *kvm)
> > +{
> > + return kvm->arch.vm_type != KVM_X86_PROTECTED_VM;
> > +}
> > +
>
> Maybe introduce a new x86 ops for SNP/TDX to check this separately as SNP
> might still support it? With the current approach, I think both SNP/TDX
> will be affected. So does the later patch about page-tracking.
This patch is unnecessary, the plan is to disallow dirty logging on memslots that
support private mapping, e.g. we'll end up with something like this:
static int check_memory_region_flags(struct kvm *kvm,
const struct kvm_userspace_memory_region2 *mem)
{
u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
if (kvm_arch_has_private_mem(kvm))
valid_flags |= KVM_MEM_PRIVATE;
/* Dirty logging private memory is not currently supported. */
if (mem->flags & KVM_MEM_PRIVATE)
valid_flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
#ifdef __KVM_HAVE_READONLY_MEM
valid_flags |= KVM_MEM_READONLY;
#endif
if (mem->flags & ~valid_flags)
return -EINVAL;
return 0;
}
> Michael, can you confirm this?
No need to confirm (or deny) at this point, enabling dirty logging for private
memory is not something I want to merge in the initial TDX/SNP series, regardless
of whether or not it's supported by "hardware", a.k.a. trusted firmware.
