Messages in this thread | | | Date | Tue, 12 Mar 2024 12:26:35 +1300 | Subject | Re: [PATCH 04/21] KVM: x86/mmu: Allow non-zero value for non-present SPTE and removed SPTE | From | "Huang, Kai" <> |
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> > +/* > + * Non-present SPTE value for both VMX and SVM for TDP MMU.
In the previous patch, SHADOW_NONPRESENT_VALUE is also used in the shadow MMU code. So here when you change SHADOW_NONPRESENT_VALUE to a non-zero value, the "for TDP MMU" part doesn't stand.
I am wondering whether we can just avoid using SHADOW_NONPRESENT_VALUE in shadow MMU code in the previous patch, and state explicitly that we are only going to support TDP MMU for non-zero value for non-present SPTE?
> + * For SVM NPT, for non-present spte (bit 0 = 0), other bits are ignored. > + * For VMX EPT, bit 63 is ignored if #VE is disabled. (EPT_VIOLATION_VE=0) > + * bit 63 is #VE suppress if #VE is enabled. (EPT_VIOLATION_VE=1) > + * For TDX: > + * TDX module sets EPT_VIOLATION_VE for Secure-EPT and conventional EPT > + */ > +#ifdef CONFIG_X86_64 > +#define SHADOW_NONPRESENT_VALUE BIT_ULL(63) > +static_assert(!(SHADOW_NONPRESENT_VALUE & SPTE_MMU_PRESENT_MASK)); > +#else > #define SHADOW_NONPRESENT_VALUE 0ULL > +#endif > > extern u64 __read_mostly shadow_host_writable_mask; > extern u64 __read_mostly shadow_mmu_writable_mask; > @@ -196,7 +209,7 @@ extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask; > * > * Only used by the TDP MMU. > */ > -#define REMOVED_SPTE 0x5a0ULL > +#define REMOVED_SPTE (SHADOW_NONPRESENT_VALUE | 0x5a0ULL)
I kinda prefer moving this chunk to the previous patch, because the reason to have SHADOW_NONPRESENT_VALUE is to have a non-zero value for non-present SPTEs, which include the REMOVED_SPTE.
But just my 2cents.
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