[PATCH v2 0/4] KVM: x86: selftests: Add Hygon CPUs support and fix failures

[PATCH v2 0/4] KVM: x86: selftests: Add Hygon CPUs support and fix failures

[Zhiquan Li]

This series to add support for Hygon CPUs and fix 11 KVM selftest failures
on Hygon architecture.

Patch 1 add CPU vendor detection for Hygon and add a global variable
"host_cpu_is_hygon" to identify if the test is running on a Hygon CPU.
It is the prerequisite for the following fixes.

Patch 2 add a flag to identify AMD compatible CPU and figure out the
compatible cases, so that Hygon CPUs can re-use them.
Following test failures on Hygon platform can be fixed by this patch:
- 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
- x86/fix_hypercall_test

Patch 3 fix x86/pmu_event_filter_test failure by allowing the tests for
Hygon CPUs.

Patch 4 fix x86/msrs_test failure while writing the MSR_TSC_AUX reserved
bits without RDPID support.
Sean has made a perfect solution for the issue and provided the patch.
It has been verified on Intel, AMD and Hygon platforms, no regression.

---

V1: https://lore.kernel.org/kvm/20260209041305.64906-1-zhiquan_li@163.com/T/#t

Changes since V1:
- Rebased to kvm-x86/next.
- Followed Sean's suggestion, added a flag to identify AMD compatible test
  cases, then v1/patch 2 and v1/patch 3 can be combined to v2/patch 2.
- Followed Sean's suggestion, simplified patch 4, that is v2/patch 3 now.
- Sean provided the v2/patch 4 for the issue reported by v1/patch5, I
  replaced my SoB with "Reported-by" tag.

---

Sean Christopherson (1):
  KVM: selftests: Fix reserved value WRMSR testcase for multi-feature
    MSRs

Zhiquan Li (3):
  KVM: x86: selftests: Add CPU vendor detection for Hygon
  KVM: x86: selftests: Add a flag to identify AMD compatible test cases
  KVM: x86: selftests: Allow the PMU event filter test for Hygon

 .../testing/selftests/kvm/include/x86/processor.h |  7 +++++++
 tools/testing/selftests/kvm/lib/x86/processor.c   | 15 +++++++++++----
 .../selftests/kvm/x86/fix_hypercall_test.c        |  2 +-
 tools/testing/selftests/kvm/x86/msrs_test.c       |  4 ++--
 .../selftests/kvm/x86/pmu_event_filter_test.c     |  3 ++-
 .../testing/selftests/kvm/x86/xapic_state_test.c  |  2 +-
 6 files changed, 24 insertions(+), 9 deletions(-)


base-commit: e944fe2c09f405a2e2d147145c9b470084bc4c9a
-- 
2.43.0

[PATCH v2 1/4] KVM: x86: selftests: Add CPU vendor detection for Hygon

[Zhiquan Li]

Currently some KVM selftests are failed on Hygon CPUs due to missing
vendor detection and edge-case handling specific to Hygon's
architecture.

Add CPU vendor detection for Hygon and add a global variable
"host_cpu_is_hygon" as the basic facility for the following fixes.

Signed-off-by: Zhiquan Li <zhiquan_li@163.com>
---
 tools/testing/selftests/kvm/include/x86/processor.h | 6 ++++++
 tools/testing/selftests/kvm/lib/x86/processor.c     | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index 4ebae4269e68..1338de7111e7 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -21,6 +21,7 @@
 
 extern bool host_cpu_is_intel;
 extern bool host_cpu_is_amd;
+extern bool host_cpu_is_hygon;
 extern uint64_t guest_tsc_khz;
 
 #ifndef MAX_NR_CPUID_ENTRIES
@@ -694,6 +695,11 @@ static inline bool this_cpu_is_amd(void)
 	return this_cpu_vendor_string_is("AuthenticAMD");
 }
 
+static inline bool this_cpu_is_hygon(void)
+{
+	return this_cpu_vendor_string_is("HygonGenuine");
+}
+
 static inline uint32_t __this_cpu_has(uint32_t function, uint32_t index,
 				      uint8_t reg, uint8_t lo, uint8_t hi)
 {
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index fab18e9be66c..f6b1c5324931 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -23,6 +23,7 @@
 vm_vaddr_t exception_handlers;
 bool host_cpu_is_amd;
 bool host_cpu_is_intel;
+bool host_cpu_is_hygon;
 bool is_forced_emulation_enabled;
 uint64_t guest_tsc_khz;
 
@@ -792,6 +793,7 @@ 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, is_forced_emulation_enabled);
 	sync_global_to_guest(vm, pmu_errata_mask);
 
@@ -1424,6 +1426,7 @@ 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();
 	is_forced_emulation_enabled = kvm_is_forced_emulation_enabled();
 
 	kvm_init_pmu_errata();
-- 
2.43.0

[PATCH v2 2/4] KVM: x86: selftests: Add a flag to identify AMD compatible test cases

[Zhiquan Li]

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>
---
 tools/testing/selftests/kvm/include/x86/processor.h  |  1 +
 tools/testing/selftests/kvm/lib/x86/processor.c      | 12 ++++++++----
 tools/testing/selftests/kvm/x86/fix_hypercall_test.c |  2 +-
 tools/testing/selftests/kvm/x86/msrs_test.c          |  2 +-
 tools/testing/selftests/kvm/x86/xapic_state_test.c   |  2 +-
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index 1338de7111e7..40e3deb64812 100644
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -22,6 +22,7 @@
 extern bool host_cpu_is_intel;
 extern bool host_cpu_is_amd;
 extern bool host_cpu_is_hygon;
+extern bool host_cpu_is_amd_compatible;
 extern uint64_t guest_tsc_khz;
 
 #ifndef MAX_NR_CPUID_ENTRIES
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();
diff --git a/tools/testing/selftests/kvm/x86/fix_hypercall_test.c b/tools/testing/selftests/kvm/x86/fix_hypercall_test.c
index 762628f7d4ba..00b6e85735dd 100644
--- a/tools/testing/selftests/kvm/x86/fix_hypercall_test.c
+++ b/tools/testing/selftests/kvm/x86/fix_hypercall_test.c
@@ -52,7 +52,7 @@ static void guest_main(void)
 	if (host_cpu_is_intel) {
 		native_hypercall_insn = vmx_vmcall;
 		other_hypercall_insn  = svm_vmmcall;
-	} else if (host_cpu_is_amd) {
+	} else if (host_cpu_is_amd_compatible) {
 		native_hypercall_insn = svm_vmmcall;
 		other_hypercall_insn  = vmx_vmcall;
 	} else {
diff --git a/tools/testing/selftests/kvm/x86/msrs_test.c b/tools/testing/selftests/kvm/x86/msrs_test.c
index 40d918aedce6..4c97444fdefe 100644
--- a/tools/testing/selftests/kvm/x86/msrs_test.c
+++ b/tools/testing/selftests/kvm/x86/msrs_test.c
@@ -81,7 +81,7 @@ static u64 fixup_rdmsr_val(u32 msr, u64 want)
 	 * is supposed to emulate that behavior based on guest vendor model
 	 * (which is the same as the host vendor model for this test).
 	 */
-	if (!host_cpu_is_amd)
+	if (!host_cpu_is_amd_compatible)
 		return want;
 
 	switch (msr) {
diff --git a/tools/testing/selftests/kvm/x86/xapic_state_test.c b/tools/testing/selftests/kvm/x86/xapic_state_test.c
index 3b4814c55722..0c5e12f5f14e 100644
--- a/tools/testing/selftests/kvm/x86/xapic_state_test.c
+++ b/tools/testing/selftests/kvm/x86/xapic_state_test.c
@@ -248,7 +248,7 @@ int main(int argc, char *argv[])
 	 * drops writes, AMD does not).  Account for the errata when checking
 	 * that KVM reads back what was written.
 	 */
-	x.has_xavic_errata = host_cpu_is_amd &&
+	x.has_xavic_errata = host_cpu_is_amd_compatible &&
 			     get_kvm_amd_param_bool("avic");
 
 	vcpu_clear_cpuid_feature(x.vcpu, X86_FEATURE_X2APIC);
-- 
2.43.0

[PATCH v2 3/4] KVM: x86: selftests: Allow the PMU event filter test for Hygon

[Zhiquan Li]

At present, the PMU event filter test for AMD architecture is applicable
for Hygon architecture as well.  Since all known Hygon processors can
re-use the test cases, so it isn't necessary to create a new wrapper.

Signed-off-by: Zhiquan Li <zhiquan_li@163.com>
---
 tools/testing/selftests/kvm/x86/pmu_event_filter_test.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86/pmu_event_filter_test.c
index 1c5b7611db24..bbd1157ef28e 100644
--- a/tools/testing/selftests/kvm/x86/pmu_event_filter_test.c
+++ b/tools/testing/selftests/kvm/x86/pmu_event_filter_test.c
@@ -361,7 +361,8 @@ static bool use_intel_pmu(void)
  */
 static bool use_amd_pmu(void)
 {
-	return host_cpu_is_amd && kvm_cpu_family() >= 0x17;
+	return (host_cpu_is_amd && kvm_cpu_family() >= 0x17) ||
+		host_cpu_is_hygon;
 }
 
 /*
-- 
2.43.0

[PATCH v2 4/4] KVM: selftests: Fix reserved value WRMSR testcase for multi-feature MSRs

[Zhiquan Li]

From: Sean Christopherson <seanjc@google.com>

When determining whether or not a WRMSR with reserved bits will #GP or
succeed due to the WRMSR not existing per the guest virtual CPU model,
expect failure if and only if _all_ features associated with the MSR are
unsupported.  Checking only the primary feature results in false failures
when running on AMD and Hygon CPUs with only one of RDPID or RDTSCP, as
AMD/Hygon CPUs ignore MSR_TSC_AUX[63:32], i.e. don't treat the bits as
reserved, and so #GP only if the MSR is unsupported.

Fixes: 9c38ddb3df94 ("KVM: selftests: Add an MSR test to exercise guest/host and read/write")
Reported-by: Zhiquan Li <zhiquan_li@163.com>
Closes: https://lore.kernel.org/all/20260209041305.64906-6-zhiquan_li@163.com
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 tools/testing/selftests/kvm/x86/msrs_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/x86/msrs_test.c b/tools/testing/selftests/kvm/x86/msrs_test.c
index 4c97444fdefe..f7e39bf887ad 100644
--- a/tools/testing/selftests/kvm/x86/msrs_test.c
+++ b/tools/testing/selftests/kvm/x86/msrs_test.c
@@ -175,7 +175,7 @@ void guest_test_reserved_val(const struct kvm_msr *msr)
 	 * If the CPU will truncate the written value (e.g. SYSENTER on AMD),
 	 * expect success and a truncated value, not #GP.
 	 */
-	if (!this_cpu_has(msr->feature) ||
+	if ((!this_cpu_has(msr->feature) && !this_cpu_has(msr->feature2)) ||
 	    msr->rsvd_val == fixup_rdmsr_val(msr->index, msr->rsvd_val)) {
 		u8 vec = wrmsr_safe(msr->index, msr->rsvd_val);
 
-- 
2.43.0

Re: [PATCH v2 0/4] KVM: x86: selftests: Add Hygon CPUs support and fix failures

[Zhiquan Li]

On 2/12/26 18:38, Zhiquan Li wrote:
> This series to add support for Hygon CPUs and fix 11 KVM selftest failures
> on Hygon architecture.
> 
> Patch 1 add CPU vendor detection for Hygon and add a global variable
> "host_cpu_is_hygon" to identify if the test is running on a Hygon CPU.
> It is the prerequisite for the following fixes.
> 
> Patch 2 add a flag to identify AMD compatible CPU and figure out the
> compatible cases, so that Hygon CPUs can re-use them.
> Following test failures on Hygon platform can be fixed by this patch:
> - 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
> - x86/fix_hypercall_test
> 
> Patch 3 fix x86/pmu_event_filter_test failure by allowing the tests for
> Hygon CPUs.
> 
> Patch 4 fix x86/msrs_test failure while writing the MSR_TSC_AUX reserved
> bits without RDPID support.
> Sean has made a perfect solution for the issue and provided the patch.
> It has been verified on Intel, AMD and Hygon platforms, no regression.
> 

Kindly ping for any review on these.

Best Regards,
Zhiquan

> ---
> 
> V1: https://lore.kernel.org/kvm/20260209041305.64906-1-zhiquan_li@163.com/T/#t
> 
> Changes since V1:
> - Rebased to kvm-x86/next.
> - Followed Sean's suggestion, added a flag to identify AMD compatible test
>   cases, then v1/patch 2 and v1/patch 3 can be combined to v2/patch 2.
> - Followed Sean's suggestion, simplified patch 4, that is v2/patch 3 now.
> - Sean provided the v2/patch 4 for the issue reported by v1/patch5, I
>   replaced my SoB with "Reported-by" tag.
> 
> ---
> 
> Sean Christopherson (1):
>   KVM: selftests: Fix reserved value WRMSR testcase for multi-feature
>     MSRs
> 
> Zhiquan Li (3):
>   KVM: x86: selftests: Add CPU vendor detection for Hygon
>   KVM: x86: selftests: Add a flag to identify AMD compatible test cases
>   KVM: x86: selftests: Allow the PMU event filter test for Hygon
> 
>  .../testing/selftests/kvm/include/x86/processor.h |  7 +++++++
>  tools/testing/selftests/kvm/lib/x86/processor.c   | 15 +++++++++++----
>  .../selftests/kvm/x86/fix_hypercall_test.c        |  2 +-
>  tools/testing/selftests/kvm/x86/msrs_test.c       |  4 ++--
>  .../selftests/kvm/x86/pmu_event_filter_test.c     |  3 ++-
>  .../testing/selftests/kvm/x86/xapic_state_test.c  |  2 +-
>  6 files changed, 24 insertions(+), 9 deletions(-)
> 
> 
> base-commit: e944fe2c09f405a2e2d147145c9b470084bc4c9a

Re: [PATCH v2 0/4] KVM: x86: selftests: Add Hygon CPUs support and fix failures

[Sean Christopherson]

On Tue, Feb 24, 2026, Zhiquan Li wrote:
> 
> On 2/12/26 18:38, Zhiquan Li wrote:
> > This series to add support for Hygon CPUs and fix 11 KVM selftest failures
> > on Hygon architecture.
> > 
> > Patch 1 add CPU vendor detection for Hygon and add a global variable
> > "host_cpu_is_hygon" to identify if the test is running on a Hygon CPU.
> > It is the prerequisite for the following fixes.
> > 
> > Patch 2 add a flag to identify AMD compatible CPU and figure out the
> > compatible cases, so that Hygon CPUs can re-use them.
> > Following test failures on Hygon platform can be fixed by this patch:
> > - 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
> > - x86/fix_hypercall_test
> > 
> > Patch 3 fix x86/pmu_event_filter_test failure by allowing the tests for
> > Hygon CPUs.
> > 
> > Patch 4 fix x86/msrs_test failure while writing the MSR_TSC_AUX reserved
> > bits without RDPID support.
> > Sean has made a perfect solution for the issue and provided the patch.
> > It has been verified on Intel, AMD and Hygon platforms, no regression.
> > 
> 
> Kindly ping for any review on these.

They're in my queue, but I typically don't apply anything except urgent fixes
until after -rc2.

Re: [PATCH v2 0/4] KVM: x86: selftests: Add Hygon CPUs support and fix failures

[Sean Christopherson]

On Thu, 12 Feb 2026 18:38:37 +0800, Zhiquan Li wrote:
> This series to add support for Hygon CPUs and fix 11 KVM selftest failures
> on Hygon architecture.
> 
> Patch 1 add CPU vendor detection for Hygon and add a global variable
> "host_cpu_is_hygon" to identify if the test is running on a Hygon CPU.
> It is the prerequisite for the following fixes.
> 
> [...]

Applied to kvm-x86 selftests, thanks!

[1/4] KVM: x86: selftests: Add CPU vendor detection for Hygon
      https://github.com/kvm-x86/linux/commit/0c96c47d4345
[2/4] KVM: x86: selftests: Add a flag to identify AMD compatible test cases
      https://github.com/kvm-x86/linux/commit/53b2869231d3
[3/4] KVM: x86: selftests: Allow the PMU event filter test for Hygon
      https://github.com/kvm-x86/linux/commit/6b8b11ba4715
[4/4] KVM: selftests: Fix reserved value WRMSR testcase for multi-feature MSRs
      https://github.com/kvm-x86/linux/commit/9396cc1e282a

--
https://github.com/kvm-x86/linux/tree/next