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From: Vivek Goyal <vgoyal@redhat.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, x86@kernel.org,
	Paolo Bonzini <pbonzini@redhat.com>,
	Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Jim Mattson <jmattson@google.com>, Gavin Shan <gshan@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 02/10] KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info
Date: Tue, 26 May 2020 14:27:45 -0400	[thread overview]
Message-ID: <20200526182745.GA114395@redhat.com> (raw)
In-Reply-To: <20200525144125.143875-3-vkuznets@redhat.com>

On Mon, May 25, 2020 at 04:41:17PM +0200, Vitaly Kuznetsov wrote:
> 

[..]
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 0a6b35353fc7..c195f63c1086 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -767,7 +767,7 @@ struct kvm_vcpu_arch {
>  		u64 msr_val;
>  		u32 id;
>  		bool send_user_only;
> -		u32 host_apf_reason;
> +		u32 host_apf_flags;

Hi Vitaly,

What is host_apf_reason used for. Looks like it is somehow used in
context of nested guests. I hope by now you have been able to figure
it out.

Is it somehow the case of that L2 guest takes a page fault exit
and then L0 injects this event in L1 using exception. I have been
trying to read this code but can't wrap my head around it.

I am still concerned about the case of nested kvm. We have discussed
apf mechanism but never touched nested part of it. Given we are
touching code in nested kvm part, want to make sure it is not broken
in new design.

Thanks
Vivek


  reply	other threads:[~2020-05-26 18:27 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-25 14:41 [PATCH v2 00/10] KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 01/10] Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and "Page Ready" exceptions simultaneously" Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 02/10] KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info Vitaly Kuznetsov
2020-05-26 18:27   ` Vivek Goyal [this message]
2020-05-28  8:42     ` Vitaly Kuznetsov
2020-05-28 10:59       ` Paolo Bonzini
2020-06-03 19:35       ` Vivek Goyal
2020-05-25 14:41 ` [PATCH v2 03/10] KVM: rename kvm_arch_can_inject_async_page_present() to kvm_arch_can_dequeue_async_page_present() Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 04/10] KVM: introduce kvm_read_guest_offset_cached() Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 05/10] KVM: x86: interrupt based APF 'page ready' event delivery Vitaly Kuznetsov
2020-06-09 19:10   ` Vivek Goyal
2020-06-09 20:31     ` Paolo Bonzini
2020-06-10  9:01       ` Vitaly Kuznetsov
2020-06-10 11:34         ` Paolo Bonzini
2020-06-10 12:51         ` Vivek Goyal
2020-05-25 14:41 ` [PATCH v2 06/10] KVM: x86: acknowledgment mechanism for async pf page ready notifications Vitaly Kuznetsov
2020-05-28 11:29   ` Paolo Bonzini
2020-05-28 11:39     ` Vitaly Kuznetsov
2020-05-28 11:44       ` Paolo Bonzini
2020-05-25 14:41 ` [PATCH v2 07/10] KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 08/10] KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery Vitaly Kuznetsov
2020-06-10 20:51   ` Vivek Goyal
2020-06-10 21:06     ` Paolo Bonzini
2020-05-25 14:41 ` [PATCH v2 09/10] KVM: x86: drop KVM_PV_REASON_PAGE_READY case from kvm_handle_page_fault() Vitaly Kuznetsov
2020-05-25 14:41 ` [PATCH v2 10/10] KVM: x86: deprecate KVM_ASYNC_PF_SEND_ALWAYS Vitaly Kuznetsov
2020-05-28 11:03   ` Paolo Bonzini
2020-05-28 11:14     ` Vitaly Kuznetsov
2020-05-28 11:04 ` [PATCH v2 00/10] KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications Paolo Bonzini
2020-06-04 17:45   ` Vivek Goyal
2020-06-04 17:56     ` Paolo Bonzini

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