Commit 53a7dc0f authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Add X86_PROPERTY_* framework to retrieve CPUID values 



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 vm_compute_max_gfn() to prove
that the code works as intended.  Future patches will convert additional
selftests code.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006005125.680782-4-seanjc@google.com
parent ee379553

tools/testing/selftests/kvm/include/x86_64/processor.h

+68 −0
Original line number Diff line number Diff line
@@ -168,6 +168,48 @@ struct kvm_x86_cpu_feature { 
#define X86_FEATURE_KVM_HC_MAP_GPA_RANGE	KVM_X86_CPU_FEATURE(0x40000001, 0, EAX, 16)

#define X86_FEATURE_KVM_MIGRATION_CONTROL	KVM_X86_CPU_FEATURE(0x40000001, 0, EAX, 17)



/*

 * 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.

 */

struct kvm_x86_cpu_property {

	u32	function;

	u8	index;

	u8	reg;

	u8	lo_bit;

	u8	hi_bit;

};

#define	KVM_X86_CPU_PROPERTY(fn, idx, gpr, low_bit, high_bit)			\

({										\

	struct kvm_x86_cpu_property property = {				\

		.function = fn,							\

		.index = idx,							\

		.reg = KVM_CPUID_##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		KVM_X86_CPU_PROPERTY(0, 0, EAX, 0, 31)



#define X86_PROPERTY_MAX_KVM_LEAF		KVM_X86_CPU_PROPERTY(0x40000000, 0, EAX, 0, 31)



#define X86_PROPERTY_MAX_EXT_LEAF		KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)

#define X86_PROPERTY_MAX_PHY_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)

#define X86_PROPERTY_PHYS_ADDR_REDUCTION	KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)



#define X86_PROPERTY_MAX_CENTAUR_LEAF		KVM_X86_CPU_PROPERTY(0xC0000000, 0, EAX, 0, 31)





/* Page table bitfield declarations */

#define PTE_PRESENT_MASK        BIT_ULL(0)

#define PTE_WRITABLE_MASK       BIT_ULL(1)
@@ -455,6 +497,32 @@ static inline bool this_cpu_has(struct kvm_x86_cpu_feature feature) 
			      feature.reg, feature.bit, feature.bit);

}



static inline uint32_t this_cpu_property(struct kvm_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 kvm_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;

}



#define SET_XMM(__var, __xmm) \

	asm volatile("movq %0, %%"#__xmm : : "r"(__var) : #__xmm)

tools/testing/selftests/kvm/lib/x86_64/processor.c

+8 −10
Original line number Diff line number Diff line
@@ -1229,7 +1229,8 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm) 
{

	const unsigned long num_ht_pages = 12 << (30 - vm->page_shift); /* 12 GiB */

	unsigned long ht_gfn, max_gfn, max_pfn;

	uint32_t eax, ebx, ecx, edx, max_ext_leaf;

	uint32_t eax, ebx, ecx, edx;

	uint8_t maxphyaddr;



	max_gfn = (1ULL << (vm->pa_bits - vm->page_shift)) - 1;
@@ -1252,17 +1253,14 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm) 
	 * reduced due to SME by bits 11:6 of CPUID[0x8000001f].EBX.  Use

	 * the old conservative value if MAXPHYADDR is not enumerated.

	 */

	cpuid(0x80000000, &eax, &ebx, &ecx, &edx);

	max_ext_leaf = eax;

	if (max_ext_leaf < 0x80000008)

	if (!this_cpu_has_p(X86_PROPERTY_MAX_PHY_ADDR))

		goto done;



	cpuid(0x80000008, &eax, &ebx, &ecx, &edx);

	max_pfn = (1ULL << ((eax & 0xff) - vm->page_shift)) - 1;

	if (max_ext_leaf >= 0x8000001f) {

		cpuid(0x8000001f, &eax, &ebx, &ecx, &edx);

		max_pfn >>= (ebx >> 6) & 0x3f;

	}

	maxphyaddr = this_cpu_property(X86_PROPERTY_MAX_PHY_ADDR);

	max_pfn = (1ULL << (maxphyaddr - vm->page_shift)) - 1;



	if (this_cpu_has_p(X86_PROPERTY_PHYS_ADDR_REDUCTION))

		max_pfn >>= this_cpu_property(X86_PROPERTY_PHYS_ADDR_REDUCTION);



	ht_gfn = max_pfn - num_ht_pages;

done: