[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v4 3/4] Introduce the NVMM impl
From: |
Paolo Bonzini |
Subject: |
Re: [PATCH v4 3/4] Introduce the NVMM impl |
Date: |
Wed, 11 Mar 2020 22:44:46 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 |
On 11/03/20 22:21, Maxime Villard wrote:
>> Yes, you don't know how long that run would take. I don't know about
>> NVMM but for KVM it may even never leave if the guest is in HLT state.
> Ok, I see, thanks.
>
> In NVMM the runs are short
How do you ensure that a guest with interrupts off exits promptly?
> , the syscalls are fast, and pending signals
> cause returns to userland. Therefore, in practice, it's not a big problem,
> because (1) the window is small and (2) if we have a miss it's not going
> to take long to come back to Qemu.
>
> I see a quick kernel change I can make to reduce 95% of the window
> already in the current state. The remaining 5% will need a new
> nvmm_vcpu_kick() function.
You can also do what KVM did until a few years ago: swap the signal mask
atomically when you enter the hypervisor (e.g. unmasking SIGUSR1---this
has to be done in the kernel) and when you leave it. Then in QEMU you
keep SIGUSR1 masked and "eat" it with sigwaitinfo.
> For now this issue is unimportant and no Qemu change is required.
If you say so.
Paolo
- Re: [PATCH v4 3/4] Introduce the NVMM impl, (continued)
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Paolo Bonzini, 2020/03/02
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Maxime Villard, 2020/03/10
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Kamil Rytarowski, 2020/03/10
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Paolo Bonzini, 2020/03/10
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Maxime Villard, 2020/03/10
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Paolo Bonzini, 2020/03/11
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Maxime Villard, 2020/03/11
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Paolo Bonzini, 2020/03/11
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Maxime Villard, 2020/03/11
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Kamil Rytarowski, 2020/03/11
- Re: [PATCH v4 3/4] Introduce the NVMM impl,
Paolo Bonzini <=
- Re: [PATCH v4 3/4] Introduce the NVMM impl, Maxime Villard, 2020/03/12