From: Paolo Bonzini <pbonzini@redhat.com>
To: Vivek Goyal <vgoyal@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, x86@kernel.org,
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 05/10] KVM: x86: interrupt based APF 'page ready' event delivery
Date: Tue, 9 Jun 2020 22:31:24 +0200 [thread overview]
Message-ID: <dcdda87c-cf2f-da6f-3166-e2d0bfefce06@redhat.com> (raw)
In-Reply-To: <20200609191035.GA223235@redhat.com>
On 09/06/20 21:10, Vivek Goyal wrote:
> Hi Vitaly,
>
> Have a question about page ready events.
>
> Now we deliver PAGE_NOT_PRESENT page faults only if guest is not in
> kernel mode. So say kernel tried to access a page and we halted cpu.
> When page is available, we will inject page_ready interrupt. At
> that time we don't seem to check whether page_not_present was injected
> or not.
>
> IOW, we seem to deliver page_ready irrespective of the fact whether
> PAGE_NOT_PRESENT was delivered or not. And that means we will be
> sending page present tokens to guest. Guest will not have a state
> associated with that token and think that page_not_present has
> not been delivered yet and allocate an element in hash table for
> future page_not_present event. And that will lead to memory leak
> and token conflict etc.
Yes, and this is https://bugzilla.kernel.org/show_bug.cgi?id=208081
which I was looking at right today.
> While setting up async pf, should we keep track whether associated
> page_not_present was delivered to guest or not and deliver page_ready
> accordingly.
Yes, I think so.
Paolo
next prev parent reply other threads:[~2020-06-09 20:31 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
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 [this message]
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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