[kvm-unit-tests PATCH 03/16] x86: Add X86_PROPERTY_* framework to retrieve CPUID values
Mi, Dapeng
dapeng1.mi at linux.intel.com
Mon Jun 9 23:14:34 PDT 2025
On 5/30/2025 6:19 AM, Sean Christopherson wrote:
> Introduce X86_PROPERTY_* to allow retrieving values/properties from CPUID
> leafs, e.g. MAXPHYADDR from CPUID.0x80000008. Use the same core code as
> X86_FEATURE_*, the primary difference is that properties are multi-bit
> values, whereas features enumerate a single bit.
>
> Add this_cpu_has_p() to allow querying whether or not a property exists
> based on the maximum leaf associated with the property, e.g. MAXPHYADDR
> doesn't exist if the max leaf for 0x8000_xxxx is less than 0x8000_0008.
>
> Use the new property infrastructure in cpuid_maxphyaddr() to prove that
> the code works as intended. Future patches will convert additional code.
>
> Note, the code, nomenclature, changelog, etc. are all stolen from KVM
> selftests.
>
> Signed-off-by: Sean Christopherson <seanjc at google.com>
> ---
> lib/x86/processor.h | 109 +++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 102 insertions(+), 7 deletions(-)
>
> diff --git a/lib/x86/processor.h b/lib/x86/processor.h
> index 3ac6711d..6b61a38b 100644
> --- a/lib/x86/processor.h
> +++ b/lib/x86/processor.h
> @@ -218,13 +218,6 @@ static inline struct cpuid cpuid(u32 function)
> return cpuid_indexed(function, 0);
> }
>
> -static inline u8 cpuid_maxphyaddr(void)
> -{
> - if (raw_cpuid(0x80000000, 0).a < 0x80000008)
> - return 36;
> - return raw_cpuid(0x80000008, 0).a & 0xff;
> -}
> -
> static inline bool is_intel(void)
> {
> struct cpuid c = cpuid(0);
> @@ -329,6 +322,74 @@ struct x86_cpu_feature {
> #define X86_FEATURE_VNMI X86_CPU_FEATURE(0x8000000A, 0, EDX, 25)
> #define X86_FEATURE_AMD_PMU_V2 X86_CPU_FEATURE(0x80000022, 0, EAX, 0)
>
> +/*
> + * Same idea as X86_FEATURE_XXX, but X86_PROPERTY_XXX retrieves a multi-bit
> + * value/property as opposed to a single-bit feature. Again, pack the info
> + * into a 64-bit value to pass by value with no overhead on 64-bit builds.
> + */
> +struct x86_cpu_property {
> + u32 function;
> + u8 index;
> + u8 reg;
> + u8 lo_bit;
> + u8 hi_bit;
> +};
> +#define X86_CPU_PROPERTY(fn, idx, gpr, low_bit, high_bit) \
> +({ \
> + struct x86_cpu_property property = { \
> + .function = fn, \
> + .index = idx, \
> + .reg = gpr, \
> + .lo_bit = low_bit, \
> + .hi_bit = high_bit, \
> + }; \
> + \
> + static_assert(low_bit < high_bit); \
> + static_assert((fn & 0xc0000000) == 0 || \
> + (fn & 0xc0000000) == 0x40000000 || \
> + (fn & 0xc0000000) == 0x80000000 || \
> + (fn & 0xc0000000) == 0xc0000000); \
> + static_assert(idx < BIT(sizeof(property.index) * BITS_PER_BYTE)); \
> + property; \
> +})
> +
> +#define X86_PROPERTY_MAX_BASIC_LEAF X86_CPU_PROPERTY(0, 0, EAX, 0, 31)
> +#define X86_PROPERTY_PMU_VERSION X86_CPU_PROPERTY(0xa, 0, EAX, 0, 7)
> +#define X86_PROPERTY_PMU_NR_GP_COUNTERS X86_CPU_PROPERTY(0xa, 0, EAX, 8, 15)
> +#define X86_PROPERTY_PMU_GP_COUNTERS_BIT_WIDTH X86_CPU_PROPERTY(0xa, 0, EAX, 16, 23)
> +#define X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH X86_CPU_PROPERTY(0xa, 0, EAX, 24, 31)
> +#define X86_PROPERTY_PMU_EVENTS_MASK X86_CPU_PROPERTY(0xa, 0, EBX, 0, 7)
> +#define X86_PROPERTY_PMU_FIXED_COUNTERS_BITMASK X86_CPU_PROPERTY(0xa, 0, ECX, 0, 31)
> +#define X86_PROPERTY_PMU_NR_FIXED_COUNTERS X86_CPU_PROPERTY(0xa, 0, EDX, 0, 4)
> +#define X86_PROPERTY_PMU_FIXED_COUNTERS_BIT_WIDTH X86_CPU_PROPERTY(0xa, 0, EDX, 5, 12)
> +
> +#define X86_PROPERTY_SUPPORTED_XCR0_LO X86_CPU_PROPERTY(0xd, 0, EAX, 0, 31)
> +#define X86_PROPERTY_XSTATE_MAX_SIZE_XCR0 X86_CPU_PROPERTY(0xd, 0, EBX, 0, 31)
> +#define X86_PROPERTY_XSTATE_MAX_SIZE X86_CPU_PROPERTY(0xd, 0, ECX, 0, 31)
> +#define X86_PROPERTY_SUPPORTED_XCR0_HI X86_CPU_PROPERTY(0xd, 0, EDX, 0, 31)
> +
> +#define X86_PROPERTY_XSTATE_TILE_SIZE X86_CPU_PROPERTY(0xd, 18, EAX, 0, 31)
> +#define X86_PROPERTY_XSTATE_TILE_OFFSET X86_CPU_PROPERTY(0xd, 18, EBX, 0, 31)
> +#define X86_PROPERTY_AMX_MAX_PALETTE_TABLES X86_CPU_PROPERTY(0x1d, 0, EAX, 0, 31)
> +#define X86_PROPERTY_AMX_TOTAL_TILE_BYTES X86_CPU_PROPERTY(0x1d, 1, EAX, 0, 15)
> +#define X86_PROPERTY_AMX_BYTES_PER_TILE X86_CPU_PROPERTY(0x1d, 1, EAX, 16, 31)
> +#define X86_PROPERTY_AMX_BYTES_PER_ROW X86_CPU_PROPERTY(0x1d, 1, EBX, 0, 15)
> +#define X86_PROPERTY_AMX_NR_TILE_REGS X86_CPU_PROPERTY(0x1d, 1, EBX, 16, 31)
> +#define X86_PROPERTY_AMX_MAX_ROWS X86_CPU_PROPERTY(0x1d, 1, ECX, 0, 15)
> +
> +#define X86_PROPERTY_MAX_KVM_LEAF X86_CPU_PROPERTY(0x40000000, 0, EAX, 0, 31)
> +
> +#define X86_PROPERTY_MAX_EXT_LEAF X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
> +#define X86_PROPERTY_MAX_PHY_ADDR X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
> +#define X86_PROPERTY_MAX_VIRT_ADDR X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
> +#define X86_PROPERTY_GUEST_MAX_PHY_ADDR X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
> +#define X86_PROPERTY_SEV_C_BIT X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
> +#define X86_PROPERTY_PHYS_ADDR_REDUCTION X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
> +#define X86_PROPERTY_NR_PERFCTR_CORE X86_CPU_PROPERTY(0x80000022, 0, EBX, 0, 3)
> +#define X86_PROPERTY_NR_PERFCTR_NB X86_CPU_PROPERTY(0x80000022, 0, EBX, 10, 15)
> +
> +#define X86_PROPERTY_MAX_CENTAUR_LEAF X86_CPU_PROPERTY(0xC0000000, 0, EAX, 0, 31)
> +
> static inline u32 __this_cpu_has(u32 function, u32 index, u8 reg, u8 lo, u8 hi)
> {
> union {
> @@ -347,6 +408,40 @@ static inline bool this_cpu_has(struct x86_cpu_feature feature)
> feature.reg, feature.bit, feature.bit);
> }
>
> +static inline uint32_t this_cpu_property(struct x86_cpu_property property)
> +{
> + return __this_cpu_has(property.function, property.index,
> + property.reg, property.lo_bit, property.hi_bit);
> +}
> +
> +static __always_inline bool this_cpu_has_p(struct x86_cpu_property property)
> +{
> + uint32_t max_leaf;
> +
> + switch (property.function & 0xc0000000) {
> + case 0:
> + max_leaf = this_cpu_property(X86_PROPERTY_MAX_BASIC_LEAF);
> + break;
> + case 0x40000000:
> + max_leaf = this_cpu_property(X86_PROPERTY_MAX_KVM_LEAF);
> + break;
> + case 0x80000000:
> + max_leaf = this_cpu_property(X86_PROPERTY_MAX_EXT_LEAF);
> + break;
> + case 0xc0000000:
> + max_leaf = this_cpu_property(X86_PROPERTY_MAX_CENTAUR_LEAF);
> + }
> + return max_leaf >= property.function;
> +}
> +
> +static inline u8 cpuid_maxphyaddr(void)
> +{
> + if (!this_cpu_has_p(X86_PROPERTY_MAX_PHY_ADDR))
> + return 36;
> +
> + return this_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);
> +}
> +
> struct far_pointer32 {
> u32 offset;
> u16 selector;
LGTM.
Reviewed-by: Dapeng Mi <dapeng1.mi at linux.intel.com>
More information about the kvm-riscv
mailing list