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Tsirkin" , Pedro Barbuda , Mohamed Mediouni , Paolo Bonzini , Zhao Liu , Roman Bolshakov , Wei Liu , Phil Dennis-Jordan Subject: [PATCH v11 02/15] whpx: i386: x2apic emulation Date: Mon, 13 Apr 2026 18:52:04 +0200 Message-ID: <20260413165217.47105-3-mohamed@unpredictable.fr> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260413165217.47105-1-mohamed@unpredictable.fr> References: <20260413165217.47105-1-mohamed@unpredictable.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDEzMDE2NiBTYWx0ZWRfX2dATQn9d38Ob 6tF0ije/+VlR9qHrJHvA8sWQbXwAh5EPq6426S1wq2LE4BUw7vqO1rYTMb3EIAwDDw6LtqnqXvU 4eNIs89wqZICNZmwpWikQid5zAGu8NLtpItiJkc0TlfA30IWzTdu1Zljqy4fwFcG89bUehhRvmW B8rEAmozWcljdRX1Ual/I8A3eRQKD/qHlo/IO3sXVHICy8C0MAcr73M8wj2ea18Vn2Yq4/f2Cnr PXytKF/rb5SYLBMUyA+zLveIDBNddV71vXcKlF++W/hydZv3FBQEfggTrd4LKaxoGNiWOVe70NY 0GJrswWkItvI4mB93QWQLEdNL554nFqsbS2dc4zPWHYernMjoIUrtOxuQVI4BU= X-Proofpoint-ORIG-GUID: rk_IeUzlxogWYICjJwglqZnkkTjJ6bQ_ X-Authority-Info-Out: v=2.4 cv=d4/4CBjE c=1 sm=1 tr=0 ts=69dd1f6a cx=c_apl:c_pps:t_out a=9OgfyREA4BUYbbCgc0Y0oA==:117 a=9OgfyREA4BUYbbCgc0Y0oA==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=nj4AhdDZwDx412jv8JQA:9 X-Proofpoint-GUID: rk_IeUzlxogWYICjJwglqZnkkTjJ6bQ_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-13_03,2026-04-13_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=734 lowpriorityscore=0 adultscore=0 malwarescore=0 bulkscore=0 mlxscore=0 clxscore=1030 phishscore=0 suspectscore=0 classifier=spam authscore=0 adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2604130166 Received-SPF: pass client-ip=57.103.69.37; envelope-from=mohamed@unpredictable.fr; helo=outbound.mr.icloud.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Add x2apic emulation to WHPX for the kernel-irqchip=off case. Unfortunately, it looks like there isn't a workaround available for proper behavior of PIC interrupts when kernel-irqchip=on for Windows 10. The OS is out of support outside of extended security updates so this will not be addressed. The performance boost is quite visible for multicore guests. Signed-off-by: Mohamed Mediouni --- target/i386/whpx/whpx-all.c | 134 +++++++++++++++++++++++++++++++++++- 1 file changed, 133 insertions(+), 1 deletion(-) diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c index e56ae2b343..4127440c0c 100644 --- a/target/i386/whpx/whpx-all.c +++ b/target/i386/whpx/whpx-all.c @@ -1082,6 +1082,8 @@ HRESULT whpx_set_exception_exit_bitmap(UINT64 exceptions) /* Register for MSR and CPUID exits */ memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY)); prop.ExtendedVmExits.X64MsrExit = 1; + prop.ExtendedVmExits.X64CpuidExit = 1; + if (exceptions != 0) { prop.ExtendedVmExits.ExceptionExit = 1; } @@ -1898,6 +1900,18 @@ int whpx_vcpu_run(CPUState *cpu) WHV_REGISTER_NAME reg_names[3]; UINT32 reg_count; bool is_known_msr = 0; + uint64_t val; + + if (vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) { + val = ((uint32_t)vcpu->exit_ctx.MsrAccess.Rax) | + ((uint64_t)(vcpu->exit_ctx.MsrAccess.Rdx) << 32); + } else { + /* + * Workaround for [-Werror=maybe-uninitialized] + * with GCC. Not needed with Clang. + */ + val = 0; + } reg_names[0] = WHvX64RegisterRip; reg_names[1] = WHvX64RegisterRax; @@ -1911,7 +1925,47 @@ int whpx_vcpu_run(CPUState *cpu) && !vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite && !whpx_irqchip_in_kernel()) { is_known_msr = 1; - reg_values[1].Reg32 = (uint32_t)X86_CPU(cpu)->env.apic_bus_freq; + val = X86_CPU(cpu)->env.apic_bus_freq; + } + + if (!whpx_irqchip_in_kernel() && + vcpu->exit_ctx.MsrAccess.MsrNumber == MSR_IA32_APICBASE) { + is_known_msr = 1; + if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) { + /* Read path unreachable on Hyper-V */ + abort(); + } else { + WHV_REGISTER_VALUE reg = {.Reg64 = val}; + int msr_ret = cpu_set_apic_base(X86_CPU(cpu)->apic_state, val); + if (msr_ret < 0) { + x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0); + } + whpx_set_reg(cpu, WHvX64RegisterApicBase, reg); + } + } + + if (!whpx_irqchip_in_kernel() && + vcpu->exit_ctx.MsrAccess.MsrNumber >= MSR_APIC_START && + vcpu->exit_ctx.MsrAccess.MsrNumber <= MSR_APIC_END) { + int index = vcpu->exit_ctx.MsrAccess.MsrNumber - MSR_APIC_START; + int msr_ret; + is_known_msr = 1; + if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) { + bql_lock(); + msr_ret = apic_msr_read(X86_CPU(cpu)->apic_state, index, &val); + bql_unlock(); + reg_values[1].Reg64 = val; + if (msr_ret < 0) { + x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0); + } + } else { + bql_lock(); + msr_ret = apic_msr_write(X86_CPU(cpu)->apic_state, index, val); + bql_unlock(); + if (msr_ret < 0) { + x86_emul_raise_exception(&X86_CPU(cpu)->env, EXCP0D_GPF, 0); + } + } } /* * For all unsupported MSR access we: @@ -1921,6 +1975,11 @@ int whpx_vcpu_run(CPUState *cpu) reg_count = vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite ? 1 : 3; + if (!vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite) { + reg_values[1].Reg32 = (uint32_t)val; + reg_values[2].Reg32 = (uint32_t)(val >> 32); + } + if (!is_known_msr) { trace_whpx_unsupported_msr_access(vcpu->exit_ctx.MsrAccess.MsrNumber, vcpu->exit_ctx.MsrAccess.AccessInfo.IsWrite); @@ -1939,6 +1998,47 @@ int whpx_vcpu_run(CPUState *cpu) ret = 0; break; } + case WHvRunVpExitReasonX64Cpuid: { + WHV_REGISTER_VALUE reg_values[5] = {0}; + WHV_REGISTER_NAME reg_names[5]; + UINT32 reg_count = 5; + X86CPU *x86_cpu = X86_CPU(cpu); + CPUX86State *env = &x86_cpu->env; + + reg_names[0] = WHvX64RegisterRip; + reg_names[1] = WHvX64RegisterRax; + reg_names[2] = WHvX64RegisterRcx; + reg_names[3] = WHvX64RegisterRdx; + reg_names[4] = WHvX64RegisterRbx; + + reg_values[0].Reg64 = + vcpu->exit_ctx.VpContext.Rip + + vcpu->exit_ctx.VpContext.InstructionLength; + + reg_values[1].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRax; + reg_values[2].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRcx; + reg_values[3].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRdx; + reg_values[4].Reg64 = vcpu->exit_ctx.CpuidAccess.DefaultResultRbx; + + if (vcpu->exit_ctx.CpuidAccess.Rax == 1) { + if (cpu_has_x2apic_feature(env)) { + reg_values[2].Reg64 |= CPUID_EXT_X2APIC; + } + } + + hr = whp_dispatch.WHvSetVirtualProcessorRegisters( + whpx->partition, + cpu->cpu_index, + reg_names, reg_count, + reg_values); + + if (FAILED(hr)) { + error_report("WHPX: Failed to set CpuidAccess state " + " registers, hr=%08lx", hr); + } + ret = 0; + break; + } case WHvRunVpExitReasonException: whpx_get_registers(cpu, WHPX_LEVEL_FULL_STATE); @@ -2136,6 +2236,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms) WHV_PROCESSOR_FEATURES_BANKS processor_features; WHV_PROCESSOR_PERFMON_FEATURES perfmon_features; bool is_legacy_os = false; + UINT32 cpuidExitList[] = {1}; whpx = &whpx_global; @@ -2354,6 +2455,7 @@ int whpx_accel_init(AccelState *as, MachineState *ms) /* Register for MSR and CPUID exits */ memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY)); prop.ExtendedVmExits.X64MsrExit = 1; + prop.ExtendedVmExits.X64CpuidExit = 1; hr = whp_dispatch.WHvSetPartitionProperty( whpx->partition, @@ -2366,6 +2468,36 @@ int whpx_accel_init(AccelState *as, MachineState *ms) goto error; } + memset(&prop, 0, sizeof(WHV_PARTITION_PROPERTY)); + prop.X64MsrExitBitmap.UnhandledMsrs = 1; + if (!whpx_irqchip_in_kernel()) { + prop.X64MsrExitBitmap.ApicBaseMsrWrite = 1; + } + + hr = whp_dispatch.WHvSetPartitionProperty( + whpx->partition, + WHvPartitionPropertyCodeX64MsrExitBitmap, + &prop, + sizeof(WHV_PARTITION_PROPERTY)); + if (FAILED(hr)) { + error_report("WHPX: Failed to set MSR exit bitmap, hr=%08lx", hr); + ret = -EINVAL; + goto error; + } + + hr = whp_dispatch.WHvSetPartitionProperty( + whpx->partition, + WHvPartitionPropertyCodeCpuidExitList, + cpuidExitList, + RTL_NUMBER_OF(cpuidExitList) * sizeof(UINT32)); + + if (FAILED(hr)) { + error_report("WHPX: Failed to set partition CpuidExitList hr=%08lx", + hr); + ret = -EINVAL; + goto error; + } + /* * We do not want to intercept any exceptions from the guest, * until we actually start debugging with gdb. -- 2.50.1 (Apple Git-155)