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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: |
Tue, 30 Jun 2020 12:43:49 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
Ok, I'll review the patch to see what you've implemented. Thanks!
Paolo
On 30/06/20 12:12, Roman Bolshakov wrote:
> On Mon, Jun 29, 2020 at 04:18:46PM +0200, Paolo Bonzini wrote:
>> On 29/06/20 16:04, Roman Bolshakov wrote:
>>> My approach is based
>>> hv_vcpu_run() and should hopefully work almost anywhere where
>>> Hypervisor.framework is available because Hypervisor framework exposes
>>> timer value
>>> (https://developer.apple.com/documentation/hypervisor/vmcs_guest_vmx_timer_value)
>>> since macOS 10.10.3+.
>>
>> There are a few other constants for which it would be unwise to write
>> from userspace, so that's not a big consolation. :)
>>
>
> Hi Paolo,
>
> So, I've tried Big Sur Beta and it has exactly the same performance
> issue with hv_vcpu_run_until() while hv_vcpu_run() works as good as it
> worked on 10.15.5. I've submitted FB7827341 to Apple wrt the issue.
>
>>> I can also test how hv_vcpu_run_until() performs with HV_DEADLINE_FOREVER
>>> on the Beta. And if the performance issues with VMX-preemption timer and
>>> hv_vcpu_run_until() are fixed there.
>>
>> Thanks! The main thing to test on Big Sur would be: 1) whether the
>> preemption timer bit in the pin controls "sticks" to 0 after setting it
>
> It does not. If it's set, it stays there.
>
>> 2) whether the bit reads back as zero after
>> hv_vcpu_run_until(HV_DEADLINE_FOREVER).
>>
>
> Likewise, it's not cleared if set.
>
> As far as I understand, hv_vcpu_run_until(HV_DEADLINE_FOREVER) works
> like hv_vcpu_run() without VMX-preemption timer. Otherwise
> hv_vcpu_run_until() implicitly sets VMX-preemption timer Pin-based
> control and sets the timer value.
>
> Thanks,
> Roman
>
> Here's the patch over v2 that adds support of hv_vcpu_run_until() on Big Sur:
> diff --git a/target/i386/hvf/hvf.c b/target/i386/hvf/hvf.c
> index 317304aa1d..ad202f7358 100644
> --- a/target/i386/hvf/hvf.c
> +++ b/target/i386/hvf/hvf.c
> @@ -72,8 +72,12 @@
> #include "sysemu/accel.h"
> #include "target/i386/cpu.h"
>
> +#if defined(__MAC_10_16) && __MAC_OS_X_VERSION_MIN_REQUIRED >= __MAC_10_16
> +#define HVF_MAX_DEADLINE HV_DEADLINE_FOREVER
> +#else
> /* Maximum value of VMX-preemption timer */
> #define HVF_MAX_DEADLINE UINT32_MAX
> +#endif
>
> HVFState *hvf_state;
>
> @@ -693,6 +697,7 @@ int hvf_vcpu_exec(CPUState *cpu)
> CPUX86State *env = &x86_cpu->env;
> int ret = 0;
> uint64_t rip = 0;
> + hv_return_t r;
>
> if (hvf_process_events(cpu)) {
> return EXCP_HLT;
> @@ -718,10 +723,22 @@ int hvf_vcpu_exec(CPUState *cpu)
> /* Use VMX-preemption timer trick only if available */
> if (rvmcs(cpu->hvf_fd, VMCS_PIN_BASED_CTLS) &
> VMCS_PIN_BASED_CTLS_VMX_PREEMPT_TIMER) {
> +#if defined(__MAC_10_16) && __MAC_OS_X_VERSION_MIN_REQUIRED >= __MAC_10_16
> + r = hv_vcpu_run_until(cpu->hvf_fd,
> + atomic_read(&env->hvf_deadline));
> + } else {
> + /*
> + * Equivalent to behaviour of hv_vcpu_run() with VMX-preemption
> + * timer disabled, prone to kick loss.
> + */
> + r = hv_vcpu_run_until(cpu->hvf_fd, HVF_MAX_DEADLINE);
> + }
> +#else
> wvmcs(cpu->hvf_fd, VMCS_PREEMPTION_TIMER_VALUE,
> atomic_read(&env->hvf_deadline));
> }
> - hv_return_t r = hv_vcpu_run(cpu->hvf_fd);
> + r = hv_vcpu_run(cpu->hvf_fd);
> +#endif
> atomic_set(&env->hvf_deadline, HVF_MAX_DEADLINE);
> assert_hvf_ok(r);
>
>
- Re: [PATCH 4/8] i386: hvf: Implement CPU kick, (continued)
- 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, 2020/06/25
- 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 <=
[PATCH 8/8] MAINTAINERS: Add Cameron as HVF co-maintainer, Roman Bolshakov, 2020/06/24
Re: [PATCH 0/8] Improve synchronization between QEMU and HVF, Paolo Bonzini, 2020/06/25