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: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006005125.680782-4-seanjc@google.com

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 52e12d4..df1ba5a 100644 (file)
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -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)
 

diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 061e001..23321c1 100644 (file)
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -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: