84d4b72854
This bug fix addresses the incorrect return value of kvm_hv_handle_exit for
KVM_EXIT_HYPERV_SYNIC, which should be EXCP_INTERRUPT.
Handling of KVM_EXIT_HYPERV_SYNIC in QEMU needs to be synchronous.
This means that async_synic_update should run in the current QEMU vCPU
thread before returning to KVM, returning EXCP_INTERRUPT to guarantee this.
Returning 0 can cause async_synic_update to run asynchronously.
One problem (kvm-unit-tests's hyperv_synic test fails with timeout error)
caused by this bug:
When a guest VM writes to the HV_X64_MSR_SCONTROL MSR to enable Hyper-V SynIC,
a VM exit is triggered and processed by the kvm_hv_handle_exit function of the
QEMU vCPU. This function then calls the async_synic_update function to set
synic->sctl_enabled to true. A true value of synic->sctl_enabled is required
before creating SINT routes using the hyperv_sint_route_new() function.
If kvm_hv_handle_exit returns 0 for KVM_EXIT_HYPERV_SYNIC, the current QEMU
vCPU thread may return to KVM and enter the guest VM before running
async_synic_update. In such case, the hyperv_synic test’s subsequent call to
synic_ctl(HV_TEST_DEV_SINT_ROUTE_CREATE, ...) immediately after writing to
HV_X64_MSR_SCONTROL can cause QEMU’s hyperv_sint_route_new() function to return
prematurely (because synic->sctl_enabled is false).
If the SINT route is not created successfully, the SINT interrupt will not be
fired, resulting in a timeout error in the hyperv_synic test.
Fixes: 267e071bd6
(“hyperv: make overlay pages for SynIC”)
Suggested-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Dongsheng Zhang <dongsheng.x.zhang@intel.com>
Message-ID: <20240521200114.11588-1-dongsheng.x.zhang@intel.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
157 lines
4.9 KiB
C
157 lines
4.9 KiB
C
/*
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* QEMU KVM Hyper-V support
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*
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* Copyright (C) 2015 Andrey Smetanin <asmetanin@virtuozzo.com>
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*
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* Authors:
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* Andrey Smetanin <asmetanin@virtuozzo.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu/main-loop.h"
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#include "hyperv.h"
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#include "hw/hyperv/hyperv.h"
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#include "hyperv-proto.h"
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int hyperv_x86_synic_add(X86CPU *cpu)
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{
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hyperv_synic_add(CPU(cpu));
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return 0;
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}
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/*
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* All devices possibly using SynIC have to be reset before calling this to let
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* them remove their SINT routes first.
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*/
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void hyperv_x86_synic_reset(X86CPU *cpu)
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{
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hyperv_synic_reset(CPU(cpu));
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}
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void hyperv_x86_synic_update(X86CPU *cpu)
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{
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CPUX86State *env = &cpu->env;
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bool enable = env->msr_hv_synic_control & HV_SYNIC_ENABLE;
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hwaddr msg_page_addr = (env->msr_hv_synic_msg_page & HV_SIMP_ENABLE) ?
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(env->msr_hv_synic_msg_page & TARGET_PAGE_MASK) : 0;
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hwaddr event_page_addr = (env->msr_hv_synic_evt_page & HV_SIEFP_ENABLE) ?
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(env->msr_hv_synic_evt_page & TARGET_PAGE_MASK) : 0;
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hyperv_synic_update(CPU(cpu), enable, msg_page_addr, event_page_addr);
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}
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static void async_synic_update(CPUState *cs, run_on_cpu_data data)
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{
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bql_lock();
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hyperv_x86_synic_update(X86_CPU(cs));
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bql_unlock();
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}
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int kvm_hv_handle_exit(X86CPU *cpu, struct kvm_hyperv_exit *exit)
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{
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CPUX86State *env = &cpu->env;
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switch (exit->type) {
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case KVM_EXIT_HYPERV_SYNIC:
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if (!hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNIC)) {
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return -1;
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}
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switch (exit->u.synic.msr) {
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case HV_X64_MSR_SCONTROL:
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env->msr_hv_synic_control = exit->u.synic.control;
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break;
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case HV_X64_MSR_SIMP:
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env->msr_hv_synic_msg_page = exit->u.synic.msg_page;
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break;
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case HV_X64_MSR_SIEFP:
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env->msr_hv_synic_evt_page = exit->u.synic.evt_page;
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break;
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default:
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return -1;
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}
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/*
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* this will run in this cpu thread before it returns to KVM, but in a
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* safe environment (i.e. when all cpus are quiescent) -- this is
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* necessary because memory hierarchy is being changed
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*/
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async_safe_run_on_cpu(CPU(cpu), async_synic_update, RUN_ON_CPU_NULL);
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return EXCP_INTERRUPT;
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case KVM_EXIT_HYPERV_HCALL: {
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uint16_t code = exit->u.hcall.input & 0xffff;
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bool fast = exit->u.hcall.input & HV_HYPERCALL_FAST;
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uint64_t in_param = exit->u.hcall.params[0];
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uint64_t out_param = exit->u.hcall.params[1];
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switch (code) {
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case HV_POST_MESSAGE:
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exit->u.hcall.result = hyperv_hcall_post_message(in_param, fast);
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break;
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case HV_SIGNAL_EVENT:
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exit->u.hcall.result = hyperv_hcall_signal_event(in_param, fast);
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break;
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case HV_POST_DEBUG_DATA:
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exit->u.hcall.result =
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hyperv_hcall_post_dbg_data(in_param, out_param, fast);
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break;
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case HV_RETRIEVE_DEBUG_DATA:
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exit->u.hcall.result =
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hyperv_hcall_retreive_dbg_data(in_param, out_param, fast);
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break;
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case HV_RESET_DEBUG_SESSION:
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exit->u.hcall.result =
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hyperv_hcall_reset_dbg_session(out_param);
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break;
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default:
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exit->u.hcall.result = HV_STATUS_INVALID_HYPERCALL_CODE;
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}
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return 0;
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}
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case KVM_EXIT_HYPERV_SYNDBG:
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if (!hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNDBG)) {
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return -1;
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}
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switch (exit->u.syndbg.msr) {
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case HV_X64_MSR_SYNDBG_CONTROL: {
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uint64_t control = exit->u.syndbg.control;
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env->msr_hv_syndbg_control = control;
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env->msr_hv_syndbg_send_page = exit->u.syndbg.send_page;
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env->msr_hv_syndbg_recv_page = exit->u.syndbg.recv_page;
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exit->u.syndbg.status = HV_STATUS_SUCCESS;
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if (control & HV_SYNDBG_CONTROL_SEND) {
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exit->u.syndbg.status =
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hyperv_syndbg_send(env->msr_hv_syndbg_send_page,
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HV_SYNDBG_CONTROL_SEND_SIZE(control));
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} else if (control & HV_SYNDBG_CONTROL_RECV) {
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exit->u.syndbg.status =
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hyperv_syndbg_recv(env->msr_hv_syndbg_recv_page,
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TARGET_PAGE_SIZE);
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}
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break;
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}
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case HV_X64_MSR_SYNDBG_PENDING_BUFFER:
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env->msr_hv_syndbg_pending_page = exit->u.syndbg.pending_page;
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hyperv_syndbg_set_pending_page(env->msr_hv_syndbg_pending_page);
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break;
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default:
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return -1;
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}
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return 0;
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default:
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return -1;
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}
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}
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void hyperv_x86_set_vmbus_recommended_features_enabled(void)
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{
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hyperv_set_vmbus_recommended_features_enabled();
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}
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