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Re: [PATCH 4/8] i386: hvf: Implement CPU kick
From: |
Paolo Bonzini |
Subject: |
Re: [PATCH 4/8] i386: hvf: Implement CPU kick |
Date: |
Thu, 25 Jun 2020 12:28:26 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 25/06/20 00:58, Roman Bolshakov wrote:
> HVF doesn't have a CPU kick and without it it's not possible to perform
> an action on CPU thread until a VMEXIT happens. The kick is also needed
> for timely interrupt delivery.
>
> Existing implementation of CPU kick sends SIG_IPI (aka SIGUSR1) to vCPU
> thread, but it's different from what hv_vcpu_interrupt does. The latter
> one results in invocation of mp_cpus_kick() in XNU kernel [1].
>
> While at it, correct type of hvf_fd to the type of hv_vcpuid_t to avoid
> compilation warnings.
>
> 1. https://opensource.apple.com/source/xnu/xnu-6153.81.5/osfmk/i386/mp.c
>
> Cc: Cameron Esfahani <dirty@apple.com>
> Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
> ---
> cpus.c | 13 +++++++++----
> include/hw/core/cpu.h | 2 +-
> include/sysemu/hvf.h | 1 +
> target/i386/hvf/hvf.c | 11 +++++++++++
> 4 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/cpus.c b/cpus.c
> index 26709677d3..36f38ce5c8 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1783,10 +1783,15 @@ static void qemu_cpu_kick_thread(CPUState *cpu)
> return;
> }
> cpu->thread_kicked = true;
> - err = pthread_kill(cpu->thread->thread, SIG_IPI);
> - if (err && err != ESRCH) {
> - fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
> - exit(1);
> +
> + if (hvf_enabled()) {
> + hvf_vcpu_kick(cpu);
> + } else {
> + err = pthread_kill(cpu->thread->thread, SIG_IPI);
> + if (err && err != ESRCH) {
> + fprintf(stderr, "qemu:%s: %s", __func__, strerror(err));
> + exit(1);
> + }
> }
> #else /* _WIN32 */
> if (!qemu_cpu_is_self(cpu)) {
> diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
> index b3f4b79318..288a2bd57e 100644
> --- a/include/hw/core/cpu.h
> +++ b/include/hw/core/cpu.h
> @@ -438,7 +438,7 @@ struct CPUState {
>
> struct hax_vcpu_state *hax_vcpu;
>
> - int hvf_fd;
> + unsigned hvf_fd;
>
> /* track IOMMUs whose translations we've cached in the TCG TLB */
> GArray *iommu_notifiers;
> diff --git a/include/sysemu/hvf.h b/include/sysemu/hvf.h
> index 1d40a8ec01..aaa00cbf05 100644
> --- a/include/sysemu/hvf.h
> +++ b/include/sysemu/hvf.h
> @@ -25,6 +25,7 @@ extern bool hvf_allowed;
>
> int hvf_init_vcpu(CPUState *);
> int hvf_vcpu_exec(CPUState *);
> +void hvf_vcpu_kick(CPUState *);
> void hvf_cpu_synchronize_state(CPUState *);
> void hvf_cpu_synchronize_post_reset(CPUState *);
> void hvf_cpu_synchronize_post_init(CPUState *);
> diff --git a/target/i386/hvf/hvf.c b/target/i386/hvf/hvf.c
> index efe9802962..4d254a477a 100644
> --- a/target/i386/hvf/hvf.c
> +++ b/target/i386/hvf/hvf.c
> @@ -966,6 +966,17 @@ int hvf_vcpu_exec(CPUState *cpu)
> return ret;
> }
>
> +void hvf_vcpu_kick(CPUState *cpu)
> +{
> + hv_return_t err;
> +
> + err = hv_vcpu_interrupt(&cpu->hvf_fd, 1);
> + if (err) {
> + fprintf(stderr, "qemu:%s error %#x\n", __func__, err);
> + exit(1);
> + }
> +}
> +
> bool hvf_allowed;
>
> static int hvf_accel_init(MachineState *ms)
>
The documentation isn't clear on whether hv_vcpu_interrupt is able to
interrupt a *subsequent* hv_vcpu_run, similar to WHPX
WHvCancelRunVirtualProcessor (is it possible to decompile
hv_vcpu_interrupt and see what it does?). If not, you can reduce a bit
the race window by setting a variable in cpu, like
atomic_set(&cpu->deadline, 0);
hv_vcpu_interrupt(...)
and in the vCPU thread
hv_vcpu_run_until(..., atomic_read(&cpu->deadline));
atomic_set(&cpu->deadline, HV_DEADLINE_FOREVER);
Paolo
- Re: [PATCH 6/8] i386: hvf: Drop hvf_reset_vcpu(), (continued)
[PATCH 5/8] i386: hvf: Don't duplicate register reset, Roman Bolshakov, 2020/06/24
[PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/24
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Claudio Fontana, 2020/06/25
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick,
Paolo Bonzini <=
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/25
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Paolo Bonzini, 2020/06/25
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Paolo Bonzini, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Paolo Bonzini, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Paolo Bonzini, 2020/06/29
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Roman Bolshakov, 2020/06/30
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, Paolo Bonzini, 2020/06/30