On Wed, 2022-04-06 at 23:06 +1200, Kai Huang wrote:
> > void kvm_mmu_reset_all_pte_masks(void)
> > {
> > u8 low_phys_bits;
> > - u64 mask;
> >
> > shadow_phys_bits = kvm_get_shadow_phys_bits();
> >
> > @@ -389,9 +383,13 @@ void kvm_mmu_reset_all_pte_masks(void)
> > * PTEs and so the reserved PA approach must be disabled.
> > */
> > if (shadow_phys_bits < 52)
> > - mask = BIT_ULL(51) | PT_PRESENT_MASK;
> > + shadow_default_mmio_mask = BIT_ULL(51) | PT_PRESENT_MASK;
>
> Hmm... Not related to this patch, but it seems there's a bug here. On a
> MKTME
> enabled system (but not TDX) with 52 physical bits, the shadow_phys_bits will
> be
> set to < 52 (depending on how many MKTME KeyIDs are configured by BIOS). In
> this case, bit 51 is set, but actually bit 51 isn't a reserved bit in this
> case.
> Instead, it is a MKTME KeyID bit. Therefore, above setting won't cause #PF,
> but
> will use a non-zero MKTME keyID to access the physical address.
>
> Paolo/Sean, any comments here?
After looking at the code more carefully, this is not correct. shadow_phys_bits
will be 52 on a MKTME-enabled system. Please ignore this.
--
Thanks,
-Kai
