> >+#define VMX_BASIC_FEATURES_MASK \
> >+ (VMX_BASIC_DUAL_MONITOR_TREATMENT | \
> >+ VMX_BASIC_INOUT | \
> >+ VMX_BASIC_TRUE_CTLS)
> >+
> >+#define VMX_BASIC_RESERVED_BITS \
> >+ (GENMASK_ULL(63, 56) | GENMASK_ULL(47, 45) | BIT_ULL(31))
>
> When we add a new feature (e.g., in CET series, bit 56 is added), the above
> two macros need to be modified.
>
> Would it be better to use a macro for bits exempt from the bitwise check below
> e.g.,
>
> #define VMX_BASIC_MULTI_BITS_FEATURES_MASK
>
> (GENMASK_ULL(53, 50) | GENMASK_ULL(44, 32) | GENMASK_ULL(30, 0))
>
> and do
> if (!is_bitwise_subset(vmx_basic, data,
> ~VMX_BASIC_MULTI_BITS_FEATURES_MASK)
>
> then we don't need to change the macro when adding new features.
Sounds a good idea to me, and just need to add comments about why.
>
> >+
> > static int vmx_restore_vmx_basic(struct vcpu_vmx *vmx, u64 data)
> > {
> >- const u64 feature_and_reserved =
> >- /* feature (except bit 48; see below) */
> >- BIT_ULL(49) | BIT_ULL(54) | BIT_ULL(55) |
> >- /* reserved */
> >- BIT_ULL(31) | GENMASK_ULL(47, 45) | GENMASK_ULL(63, 56);
> > u64 vmx_basic = vmcs_config.nested.basic;
> >
> >- if (!is_bitwise_subset(vmx_basic, data, feature_and_reserved))
> >+ static_assert(!(VMX_BASIC_FEATURES_MASK &
> VMX_BASIC_RESERVED_BITS));
> >+
> >+ if (!is_bitwise_subset(vmx_basic, data,
> >+ VMX_BASIC_FEATURES_MASK |
> VMX_BASIC_RESERVED_BITS))
> > return -EINVAL;
> >
> > /*
> > * KVM does not emulate a version of VMX that constrains physical
> > * addresses of VMX structures (e.g. VMCS) to 32-bits.
> > */
> >- if (data & BIT_ULL(48))
> >+ if (data & VMX_BASIC_32BIT_PHYS_ADDR_ONLY)
> > return -EINVAL;
>
> Side topic:
>
> Actually, there is no need to handle bit 48 as a special case. If we add bit 48
> to VMX_BASIC_FEATURES_MASK, the bitwise check will fail if bit 48 of @data is 1.
Good point! This is also what you suggested above.
