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GET /api/patches/2219594/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "id": 2219594,
    "url": "http://patchwork.ozlabs.org/api/patches/2219594/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260403142446.36964-3-mohamed@unpredictable.fr/",
    "project": {
        "id": 14,
        "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api",
        "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": "",
        "list_archive_url": "",
        "list_archive_url_format": "",
        "commit_url_format": ""
    },
    "msgid": "<20260403142446.36964-3-mohamed@unpredictable.fr>",
    "list_archive_url": null,
    "date": "2026-04-03T14:24:39",
    "name": "[v5,2/9] whpx: i386: x2apic emulation",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "ebac3004b414e1e140587e833b3fa5c9dcb9877e",
    "submitter": {
        "id": 91318,
        "url": "http://patchwork.ozlabs.org/api/people/91318/?format=api",
        "name": "Mohamed Mediouni",
        "email": "mohamed@unpredictable.fr"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260403142446.36964-3-mohamed@unpredictable.fr/mbox/",
    "series": [
        {
            "id": 498635,
            "url": "http://patchwork.ozlabs.org/api/series/498635/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=498635",
            "date": "2026-04-03T14:24:37",
            "name": "whpx: i386: bug fixes, feature probing and CPUID",
            "version": 5,
            "mbox": "http://patchwork.ozlabs.org/series/498635/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/2219594/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/2219594/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>",
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        ],
        "Dkim-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=unpredictable.fr;\n s=sig1; t=1775226302; x=1777818302;\n bh=zl2db1VwfCW29E4LtwT7zz4buZdQP1VZYTXVu1kcs+o=;\n h=From:To:Subject:Date:Message-ID:MIME-Version:x-icloud-hme;\n b=DtoL5rL7Ca/ybfi84oX7+wTkcaEw06Wp0Gv38hKIr/IGF5HEaYdYC68m7GA24kOYUYX+xwokjkbmIbC8wdln1lB+k7ccl0L5GKm7HT/t45CPuN0jSs5bc5UO0UGjrOeo0j0ddPpfqa3VQUCQ8ABcJukz4oMQdzj7Yhaz5FA1jG3p6Y6FrPcybg5teIkenpv8W4L4H4E2+PIn5MTO+ZvI8Cf6OymlO9Aw92kt2koQaNa3Ij1sg9THWpa2C+OHNaFlDiUIPASUblV0PB4dgh0A+4q/lepmxwkUehL/4vV1g3QDrKuQGbDuLxQqQPAusCGN2f3184VErU8djXMEluUYBA==",
        "mail-alias-created-date": "1752046281608",
        "From": "Mohamed Mediouni <mohamed@unpredictable.fr>",
        "To": "qemu-devel@nongnu.org",
        "Cc": "Phil Dennis-Jordan <phil@philjordan.eu>,\n Mohamed Mediouni <mohamed@unpredictable.fr>,\n Paolo Bonzini <pbonzini@redhat.com>, Zhao Liu <zhao1.liu@intel.com>,\n Pedro Barbuda <pbarbuda@microsoft.com>, Wei Liu <wei.liu@kernel.org>,\n Roman Bolshakov <rbolshakov@ddn.com>",
        "Subject": "[PATCH v5 2/9] whpx: i386: x2apic emulation",
        "Date": "Fri,  3 Apr 2026 16:24:39 +0200",
        "Message-ID": "<20260403142446.36964-3-mohamed@unpredictable.fr>",
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        "In-Reply-To": "<20260403142446.36964-1-mohamed@unpredictable.fr>",
        "References": "<20260403142446.36964-1-mohamed@unpredictable.fr>",
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    },
    "content": "Add x2apic emulation to WHPX for the kernel-irqchip=off case.\n\nUnfortunately, it looks like there isn't a workaround available\nfor proper behavior of PIC interrupts when kernel-irqchip=on\nfor Windows 10. The OS is out of support outside of extended\nsecurity updates so this will not be addressed.\n\nThe performance boost is quite visible for multicore guests.\n\nSigned-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>\n---\n target/i386/whpx/whpx-all.c | 134 +++++++++++++++++++++++++++++++++++-\n 1 file changed, 133 insertions(+), 1 deletion(-)",
    "diff": "diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c\nindex e56ae2b343..4127440c0c 100644\n--- a/target/i386/whpx/whpx-all.c\n+++ b/target/i386/whpx/whpx-all.c\n@@ -1082,6 +1082,8 @@ HRESULT whpx_set_exception_exit_bitmap(UINT64 exceptions)\n     /* Register for MSR and CPUID exits */\n     memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY));\n     prop.ExtendedVmExits.X64MsrExit = 1;\n+    prop.ExtendedVmExits.X64CpuidExit = 1;\n+\n     if (exceptions != 0) {\n         prop.ExtendedVmExits.ExceptionExit = 1;\n     }\n@@ -1898,6 +1900,18 @@ int whpx_vcpu_run(CPUState *cpu)\n             WHV_REGISTER_NAME reg_names[3];\n             UINT32 reg_count;\n             bool is_known_msr = 0; \n+            uint64_t val;\n+\n+            if (vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) {\n+                val = ((uint32_t)vcpu->exit_ctx.MsrAccess.Rax) |\n+                    ((uint64_t)(vcpu->exit_ctx.MsrAccess.Rdx) << 32);\n+            } else {\n+                /*\n+                 * Workaround for [-Werror=maybe-uninitialized]\n+                 * with GCC. Not needed with Clang.\n+                 */\n+                val = 0;\n+            }\n \n             reg_names[0] = WHvX64RegisterRip;\n             reg_names[1] = WHvX64RegisterRax;\n@@ -1911,7 +1925,47 @@ int whpx_vcpu_run(CPUState *cpu)\n                 && !vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite\n                 && !whpx_irqchip_in_kernel()) {\n                 is_known_msr = 1;\n-                reg_values[1].Reg32 = (uint32_t)X86_CPU(cpu)->env.apic_bus_freq;\n+                val = X86_CPU(cpu)->env.apic_bus_freq;\n+            }\n+\n+            if (!whpx_irqchip_in_kernel() &&\n+                vcpu->exit_ctx.MsrAccess.MsrNumber == MSR_IA32_APICBASE) {\n+                is_known_msr = 1;\n+                if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) {\n+                    /* Read path unreachable on Hyper-V */\n+                    abort();\n+                } else {\n+                    WHV_REGISTER_VALUE reg = {.Reg64 = val};\n+                    int msr_ret = cpu_set_apic_base(X86_CPU(cpu)->apic_state, val);\n+                    if (msr_ret < 0) {\n+                        x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0);\n+                    }\n+                    whpx_set_reg(cpu, WHvX64RegisterApicBase, reg);\n+                }\n+            }\n+\n+            if (!whpx_irqchip_in_kernel() &&\n+                vcpu->exit_ctx.MsrAccess.MsrNumber >= MSR_APIC_START &&\n+                vcpu->exit_ctx.MsrAccess.MsrNumber <= MSR_APIC_END) {\n+                int index = vcpu->exit_ctx.MsrAccess.MsrNumber - MSR_APIC_START;\n+                int msr_ret;\n+                is_known_msr = 1;\n+                if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) {\n+                    bql_lock();\n+                    msr_ret = apic_msr_read(X86_CPU(cpu)->apic_state, index, &val);\n+                    bql_unlock();\n+                    reg_values[1].Reg64 = val;\n+                    if (msr_ret < 0) {\n+                        x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0);\n+                    }\n+                } else {\n+                    bql_lock();\n+                    msr_ret = apic_msr_write(X86_CPU(cpu)->apic_state, index, val);\n+                    bql_unlock();\n+                    if (msr_ret < 0) {\n+                        x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0);\n+                    }\n+                }\n             }\n             /*\n              * For all unsupported MSR access we:\n@@ -1921,6 +1975,11 @@ int whpx_vcpu_run(CPUState *cpu)\n             reg_count = vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite ?\n                         1 : 3;\n \n+            if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) {\n+                reg_values[1].Reg32 = (uint32_t)val;\n+                reg_values[2].Reg32 = (uint32_t)(val >> 32);\n+            }\n+\n             if (!is_known_msr) {\n                 trace_whpx_unsupported_msr_access(vcpu->exit_ctx.MsrAccess.MsrNumber,\n                     vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite);\n@@ -1939,6 +1998,47 @@ int whpx_vcpu_run(CPUState *cpu)\n             ret = 0;\n             break;\n         }\n+        case WHvRunVpExitReasonX64Cpuid: {\n+            WHV_REGISTER_VALUE reg_values[5] = {0};\n+            WHV_REGISTER_NAME reg_names[5];\n+            UINT32 reg_count = 5;\n+            X86CPU *x86_cpu = X86_CPU(cpu);\n+            CPUX86State *env = &x86_cpu->env;\n+\n+            reg_names[0] = WHvX64RegisterRip;\n+            reg_names[1] = WHvX64RegisterRax;\n+            reg_names[2] = WHvX64RegisterRcx;\n+            reg_names[3] = WHvX64RegisterRdx;\n+            reg_names[4] = WHvX64RegisterRbx;\n+\n+            reg_values[0].Reg64 =\n+                vcpu->exit_ctx.VpContext.Rip +\n+                vcpu->exit_ctx.VpContext.InstructionLength;\n+\n+            reg_values[1].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRax;\n+            reg_values[2].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRcx;\n+            reg_values[3].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx;\n+            reg_values[4].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx;\n+\n+            if (vcpu->exit_ctx.CpuidAccess.Rax == 1) {\n+                if (cpu_has_x2apic_feature(env)) {\n+                    reg_values[2].Reg64 |= CPUID_EXT_X2APIC;\n+                }\n+            }\n+\n+            hr = whp_dispatch.WHvSetVirtualProcessorRegisters(\n+                whpx->partition,\n+                cpu->cpu_index,\n+                reg_names, reg_count,\n+                reg_values);\n+\n+            if (FAILED(hr)) {\n+                error_report(\"WHPX: Failed to set CpuidAccess state \"\n+                             \" registers, hr=%08lx\", hr);\n+            }\n+            ret = 0;\n+            break;\n+        }\n         case WHvRunVpExitReasonException:\n             whpx_get_registers(cpu, WHPX_LEVEL_FULL_STATE);\n \n@@ -2136,6 +2236,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\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 \n@@ -2354,6 +2455,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n     /* Register for MSR and CPUID exits */\n     memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY));\n     prop.ExtendedVmExits.X64MsrExit = 1;\n+    prop.ExtendedVmExits.X64CpuidExit = 1;\n \n     hr = whp_dispatch.WHvSetPartitionProperty(\n             whpx->partition,\n@@ -2366,6 +2468,36 @@ int whpx_accel_init(AccelState *as, MachineState *ms)\n         goto error;\n     }\n \n+    memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY));\n+    prop.X64MsrExitBitmap.UnhandledMsrs = 1;\n+    if (!whpx_irqchip_in_kernel()) {\n+        prop.X64MsrExitBitmap.ApicBaseMsrWrite = 1;\n+    }\n+\n+    hr = whp_dispatch.WHvSetPartitionProperty(\n+            whpx->partition,\n+            WHvPartitionPropertyCodeX64MsrExitBitmap,\n+            &prop,\n+            sizeof(WHV_PARTITION_PROPERTY));\n+    if (FAILED(hr)) {\n+        error_report(\"WHPX: Failed to set MSR exit bitmap, hr=%08lx\", hr);\n+        ret = -EINVAL;\n+        goto error;\n+    }\n+\n+    hr = whp_dispatch.WHvSetPartitionProperty(\n+        whpx->partition,\n+        WHvPartitionPropertyCodeCpuidExitList,\n+        cpuidExitList,\n+        RTL_NUMBER_OF(cpuidExitList) * sizeof(UINT32));\n+\n+    if (FAILED(hr)) {\n+        error_report(\"WHPX: Failed to set partition CpuidExitList hr=%08lx\",\n+                     hr);\n+        ret = -EINVAL;\n+        goto error;\n+    }\n+\n     /*\n      * We do not want to intercept any exceptions from the guest,\n      * until we actually start debugging with gdb.\n",
    "prefixes": [
        "v5",
        "2/9"
    ]
}