{"id":2219486,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2219486/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260403053748.78831-4-mohamed@unpredictable.fr>","date":"2026-04-03T05:37:44","name":"[v4,3/7] whpx: i386: wire up feature probing","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"0547db4fdb7870114b92541ecfb89efbed6bdb77","submitter":{"id":91318,"url":"http://patchwork.ozlabs.org/api/1.0/people/91318/?format=json","name":"Mohamed Mediouni","email":"mohamed@unpredictable.fr"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260403053748.78831-4-mohamed@unpredictable.fr/mbox/","series":[{"id":498589,"url":"http://patchwork.ozlabs.org/api/1.0/series/498589/?format=json","date":"2026-04-03T05:37:41","name":"whpx: i386: x2apic emulation for kernel-irqchip=off, feature probing","version":4,"mbox":"http://patchwork.ozlabs.org/series/498589/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2219486/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=unpredictable.fr header.i=@unpredictable.fr\n header.a=rsa-sha256 header.s=sig1 header.b=ChGUyK6v;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n 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b=ChGUyK6vi3UGw42icBDnTQdIlsgD+cNehzG6+Kif/sYXYx4EZvbV7U8F4UPFwN7R0c6sGI7oGasIYMA1+fe+o+QxxUbqFGNeDV1G1CQbSlq408sQBIoAAZDdlYmetes9F0fWJSNB60KcyRXcpMwQ/Q2JPck3o74GTKC729282Nfprf/qLvhgnoWVfkKZ67x5UR9etkxQvFoA5t7GwdzBgrIDca6GUzWWyjq1EJXKeNgUtYedgYeJgtELQzLYBG02lZv9wlv9xvlUhofKRsVEhQuhXGew/BBVEFKw6T673HS2sNNRFT9bb2HP7FAS0wwE+Yl5T/URYRiRBc9sRJZIew==","mail-alias-created-date":"1752046281608","From":"Mohamed Mediouni ","To":"qemu-devel@nongnu.org","Cc":"Wei Liu , Paolo Bonzini ,\n Zhao Liu , Pedro Barbuda ,\n Phil Dennis-Jordan ,\n Mohamed Mediouni ,\n Roman Bolshakov ","Subject":"[PATCH v4 3/7] whpx: i386: wire up feature probing","Date":"Fri, 3 Apr 2026 07:37:44 +0200","Message-ID":"<20260403053748.78831-4-mohamed@unpredictable.fr>","X-Mailer":"git-send-email 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SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Windows 10 doesn't have the API for this, so using this\nonly for Windows 11.\n\nSigned-off-by: Mohamed Mediouni \n---\n include/system/whpx-internal.h | 9 ++++\n target/i386/cpu.c | 25 ++++++++++++\n target/i386/whpx/whpx-all.c | 75 ++++++++++++++++++++++++++++++++--\n target/i386/whpx/whpx-i386.h | 4 ++\n 4 files changed, 109 insertions(+), 4 deletions(-)\n create mode 100644 target/i386/whpx/whpx-i386.h","diff":"diff --git a/include/system/whpx-internal.h b/include/system/whpx-internal.h\nindex 8482901f71..5902124b63 100644\n--- a/include/system/whpx-internal.h\n+++ b/include/system/whpx-internal.h\n@@ -73,6 +73,14 @@ void whpx_apic_get(APICCommonState *s);\n X(HRESULT, WHvGetVirtualProcessorRegisters, (WHV_PARTITION_HANDLE Partition, UINT32 VpIndex, const WHV_REGISTER_NAME* RegisterNames, UINT32 RegisterCount, WHV_REGISTER_VALUE* RegisterValues)) \\\n X(HRESULT, WHvSetVirtualProcessorRegisters, (WHV_PARTITION_HANDLE Partition, UINT32 VpIndex, const WHV_REGISTER_NAME* RegisterNames, UINT32 RegisterCount, const WHV_REGISTER_VALUE* RegisterValues)) \\\n \n+#ifdef __x86_64__\n+#define LIST_WINHVPLATFORM_FUNCTIONS_SUPPLEMENTAL_ARCH(X) \\\n+ X(HRESULT, WHvGetVirtualProcessorCpuidOutput, \\\n+ (WHV_PARTITION_HANDLE Partition, UINT32 VpIndex, UINT32 Eax, \\\n+ UINT32 Ecx, WHV_CPUID_OUTPUT *CpuidOutput))\n+#else\n+#define LIST_WINHVPLATFORM_FUNCTIONS_SUPPLEMENTAL_ARCH(X)\n+#endif\n /*\n * These are supplemental functions that may not be present\n * on all versions and are not critical for basic functionality.\n@@ -89,6 +97,7 @@ void whpx_apic_get(APICCommonState *s);\n UINT32 StateSize)) \\\n X(HRESULT, WHvResetPartition, \\\n (WHV_PARTITION_HANDLE Partition)) \\\n+ LIST_WINHVPLATFORM_FUNCTIONS_SUPPLEMENTAL_ARCH(X)\n \n #define WHP_DEFINE_TYPE(return_type, function_name, signature) \\\n typedef return_type (WINAPI *function_name ## _t) signature;\ndiff --git a/target/i386/cpu.c b/target/i386/cpu.c\nindex c6fd1dc00e..0000093fa3 100644\n--- a/target/i386/cpu.c\n+++ b/target/i386/cpu.c\n@@ -26,6 +26,8 @@\n #include \"tcg/helper-tcg.h\"\n #include \"exec/translation-block.h\"\n #include \"system/hvf.h\"\n+#include \"system/whpx.h\"\n+#include \"whpx/whpx-i386.h\"\n #include \"hvf/hvf-i386.h\"\n #include \"kvm/kvm_i386.h\"\n #include \"kvm/tdx.h\"\n@@ -8087,6 +8089,17 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w)\n r = hvf_get_supported_cpuid(wi->cpuid.eax,\n wi->cpuid.ecx,\n wi->cpuid.reg);\n+ } else if (whpx_enabled()) {\n+ if (wi->type != CPUID_FEATURE_WORD) {\n+ return 0;\n+ }\n+ if (whpx_is_legacy_os()) {\n+ r = wi->tcg_features;\n+ } else {\n+ r = whpx_get_supported_cpuid(wi->cpuid.eax,\n+ wi->cpuid.ecx,\n+ wi->cpuid.reg);\n+ }\n } else if (tcg_enabled() || qtest_enabled()) {\n r = wi->tcg_features;\n } else {\n@@ -8168,6 +8181,18 @@ static void x86_cpu_get_supported_cpuid(uint32_t func, uint32_t index,\n *ebx = hvf_get_supported_cpuid(func, index, R_EBX);\n *ecx = hvf_get_supported_cpuid(func, index, R_ECX);\n *edx = hvf_get_supported_cpuid(func, index, R_EDX);\n+ } else if (whpx_enabled()) {\n+ if (whpx_is_legacy_os()) {\n+ *eax = 0;\n+ *ebx = 0;\n+ *ecx = 0;\n+ *edx = 0;\n+ } else {\n+ *eax = whpx_get_supported_cpuid(func, index, R_EAX);\n+ *ebx = whpx_get_supported_cpuid(func, index, R_EBX);\n+ *ecx = whpx_get_supported_cpuid(func, index, R_ECX);\n+ *edx = whpx_get_supported_cpuid(func, index, R_EDX);\n+ }\n } else {\n *eax = 0;\n *ebx = 0;\ndiff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c\nindex 4127440c0c..2d527b90dd 100644\n--- a/target/i386/whpx/whpx-all.c\n+++ b/target/i386/whpx/whpx-all.c\n@@ -36,6 +36,7 @@\n #include \"system/whpx-accel-ops.h\"\n #include \"system/whpx-all.h\"\n #include \"system/whpx-common.h\"\n+#include \"whpx-i386.h\"\n \n #include \"emulate/x86_decode.h\"\n #include \"emulate/x86_emu.h\"\n@@ -49,6 +50,8 @@\n /* for kernel-irqchip=off */\n #define HV_X64_MSR_APIC_FREQUENCY 0x40000023\n \n+static bool is_modern_os = true;\n+\n static const WHV_REGISTER_NAME whpx_register_names[] = {\n \n /* X64 General purpose registers */\n@@ -1062,6 +1065,71 @@ static void whpx_init_emu(void)\n init_emu(&whpx_x86_emul_ops);\n }\n \n+bool whpx_is_legacy_os(void)\n+{\n+ return !is_modern_os;\n+}\n+\n+uint32_t whpx_get_supported_cpuid(uint32_t func, uint32_t idx, int reg)\n+{\n+ WHV_CPUID_OUTPUT output;\n+ uint32_t eax, ebx, ecx, edx;\n+ uint32_t cpu_index = 0;\n+ bool temp_cpu = true;\n+ HRESULT hr;\n+\n+ hr = whp_dispatch.WHvCreateVirtualProcessor(\n+ whpx_global.partition, cpu_index, 0);\n+\n+ /* This means that the CPU already exists... */\n+ if (FAILED(hr)) {\n+ temp_cpu = false;\n+ }\n+\n+ hr = whp_dispatch.WHvGetVirtualProcessorCpuidOutput(whpx_global.partition,\n+ cpu_index, func, idx, &output);\n+\n+ if (FAILED(hr)) {\n+ abort();\n+ }\n+\n+ if (temp_cpu) {\n+ hr = whp_dispatch.WHvDeleteVirtualProcessor(whpx_global.partition, cpu_index);\n+ if (FAILED(hr)) {\n+ abort();\n+ }\n+ }\n+\n+ eax = output.Eax;\n+ ebx = output.Ebx;\n+ ecx = output.Ecx;\n+ edx = output.Edx;\n+\n+ /*\n+ * We can emulate X2APIC even for the kernel-irqchip=off case.\n+ * CPUID_EXT_HYPERVISOR and CPUID_HT should be considered present\n+ * always, so report them as unconditionally supported here.\n+ */\n+ if (func == 1) {\n+ ecx |= CPUID_EXT_X2APIC;\n+ ecx |= CPUID_EXT_HYPERVISOR;\n+ edx |= CPUID_HT;\n+ }\n+\n+ switch (reg) {\n+ case R_EAX:\n+ return eax;\n+ case R_EBX:\n+ return ebx;\n+ case R_ECX:\n+ return ecx;\n+ case R_EDX:\n+ return edx;\n+ default:\n+ return 0;\n+ }\n+}\n+\n /*\n * Controls whether we should intercept various exceptions on the guest,\n * namely breakpoint/single-step events.\n@@ -2235,7 +2303,6 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n WHV_CAPABILITY_FEATURES features = {0};\n WHV_PROCESSOR_FEATURES_BANKS processor_features;\n WHV_PROCESSOR_PERFMON_FEATURES perfmon_features;\n- bool is_legacy_os = false;\n UINT32 cpuidExitList[] = {1};\n \n whpx = &whpx_global;\n@@ -2395,7 +2462,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n if (FAILED(hr)) {\n warn_report(\"WHPX: Failed to get performance \"\n \"monitoring features, hr=%08lx\", hr);\n- is_legacy_os = true;\n+ is_modern_os = false;\n } else {\n hr = whp_dispatch.WHvSetPartitionProperty(\n whpx->partition,\n@@ -2435,7 +2502,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n synthetic_features.Bank0.DirectSyntheticTimers = 1;\n }\n \n- if (!is_legacy_os && whpx->hyperv_enlightenments_allowed) {\n+ if (is_modern_os && whpx->hyperv_enlightenments_allowed) {\n hr = whp_dispatch.WHvSetPartitionProperty(\n whpx->partition,\n WHvPartitionPropertyCodeSyntheticProcessorFeaturesBanks,\n@@ -2446,7 +2513,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n ret = -EINVAL;\n goto error;\n }\n- } else if (is_legacy_os && whpx->hyperv_enlightenments_required) {\n+ } else if (!is_modern_os && whpx->hyperv_enlightenments_required) {\n error_report(\"Hyper-V enlightenments not available on legacy Windows\");\n ret = -EINVAL;\n goto error;\ndiff --git a/target/i386/whpx/whpx-i386.h b/target/i386/whpx/whpx-i386.h\nnew file mode 100644\nindex 0000000000..6db9a75d39\n--- /dev/null\n+++ b/target/i386/whpx/whpx-i386.h\n@@ -0,0 +1,4 @@\n+/* SPDX-License-Identifier: GPL-2.0-or-later */\n+\n+uint32_t whpx_get_supported_cpuid(uint32_t func, uint32_t idx, int reg);\n+bool whpx_is_legacy_os(void);\n","prefixes":["v4","3/7"]}