KVM: selftests: Add a flag to identify AMD compatible test cases

Most of KVM x86 selftests for AMD are compatible with Hygon architecture
(but not all), add a flag "host_cpu_is_amd_compatible" to figure out
these cases.

Following test failures on Hygon platform can be fixed:

* Fix hypercall test: Hygon architecture also uses VMMCALL as guest
  hypercall instruction.

* Following test failures due to access reserved memory address regions:
  - access_tracking_perf_test
  - demand_paging_test
  - dirty_log_perf_test
  - dirty_log_test
  - kvm_page_table_test
  - memslot_modification_stress_test
  - pre_fault_memory_test
  - x86/dirty_log_page_splitting_test

Hygon CSV also makes the "physical address space width reduction", the
reduced physical address bits are reported by bits 11:6 of
CPUID[0x8000001f].EBX as well, so the existed logic is totally
applicable for Hygon processors.  Mapping memory into these regions and
accessing to them results in a #PF.

Signed-off-by: Zhiquan Li <zhiquan_li@163.com>
Link: https://patch.msgid.link/20260212103841.171459-3-zhiquan_li@163.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index f6b1c5324931..f4e8649071b6 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -24,6 +24,7 @@ vm_vaddr_t exception_handlers;
 bool host_cpu_is_amd;
 bool host_cpu_is_intel;
 bool host_cpu_is_hygon;
+bool host_cpu_is_amd_compatible;
 bool is_forced_emulation_enabled;
 uint64_t guest_tsc_khz;
 
@@ -794,6 +795,7 @@ void kvm_arch_vm_post_create(struct kvm_vm *vm, unsigned int nr_vcpus)
 	sync_global_to_guest(vm, host_cpu_is_intel);
 	sync_global_to_guest(vm, host_cpu_is_amd);
 	sync_global_to_guest(vm, host_cpu_is_hygon);
+	sync_global_to_guest(vm, host_cpu_is_amd_compatible);
 	sync_global_to_guest(vm, is_forced_emulation_enabled);
 	sync_global_to_guest(vm, pmu_errata_mask);
 
@@ -1350,7 +1352,8 @@ const struct kvm_cpuid_entry2 *get_cpuid_entry(const struct kvm_cpuid2 *cpuid,
 		     "1: vmmcall\n\t"					\
 		     "2:"						\
 		     : "=a"(r)						\
-		     : [use_vmmcall] "r" (host_cpu_is_amd), inputs);	\
+		     : [use_vmmcall] "r" (host_cpu_is_amd_compatible),	\
+		       inputs);						\
 									\
 	r;								\
 })
@@ -1390,8 +1393,8 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm)
 
 	max_gfn = (1ULL << (guest_maxphyaddr - vm->page_shift)) - 1;
 
-	/* Avoid reserved HyperTransport region on AMD processors.  */
-	if (!host_cpu_is_amd)
+	/* Avoid reserved HyperTransport region on AMD or Hygon processors. */
+	if (!host_cpu_is_amd_compatible)
 		return max_gfn;
 
 	/* On parts with <40 physical address bits, the area is fully hidden */
@@ -1405,7 +1408,7 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm)
 
 	/*
 	 * Otherwise it's at the top of the physical address space, possibly
-	 * reduced due to SME by bits 11:6 of CPUID[0x8000001f].EBX.  Use
+	 * reduced due to SME or CSV by bits 11:6 of CPUID[0x8000001f].EBX.  Use
 	 * the old conservative value if MAXPHYADDR is not enumerated.
 	 */
 	if (!this_cpu_has_p(X86_PROPERTY_MAX_PHY_ADDR))
@@ -1427,6 +1430,7 @@ void kvm_selftest_arch_init(void)
 	host_cpu_is_intel = this_cpu_is_intel();
 	host_cpu_is_amd = this_cpu_is_amd();
 	host_cpu_is_hygon = this_cpu_is_hygon();
+	host_cpu_is_amd_compatible = host_cpu_is_amd || host_cpu_is_hygon;
 	is_forced_emulation_enabled = kvm_is_forced_emulation_enabled();
 
 	kvm_init_pmu_errata();