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From: Wanpeng Li <kernellwp@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [FYI PATCH 0/5] Missing TLB flushes
Date: Sat, 1 Feb 2020 13:53:31 +0800
Message-ID: <CANRm+CyyuWUOAj81Sg8UH_jMybZWmvZxWPWZ_twMvFnPxKD3hQ@mail.gmail.com> (raw)
In-Reply-To: <1580407316-11391-1-git-send-email-pbonzini@redhat.com>

On Fri, 31 Jan 2020 at 02:02, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
>
> The KVM hypervisor may provide a guest with ability to defer remote TLB
> flush when the remote VCPU is not running. When this feature is used,
> the TLB flush will happen only when the remote VPCU is scheduled to run
> again. This will avoid unnecessary (and expensive) IPIs.
>
> Under certain circumstances, when a guest initiates such deferred action,
> the hypervisor may miss the request. It is also possible that the guest
> may mistakenly assume that it has already marked remote VCPU as needing
> a flush when in fact that request had already been processed by the
> hypervisor. In both cases this will result in an invalid translation
> being present in a vCPU, potentially allowing accesses to memory locations
> in that guest's address space that should not be accessible.
>
> Note that only intra-guest memory is vulnerable.
>
> The attached patches address both of these problems:
> 1. The first patch makes sure the hypervisor doesn't accidentally clear
> guest's remote flush request
> 2. The rest of the patches prevent the race between hypervisor
> acknowledging a remote flush request and guest issuing a new one.

Looks good, thanks for the patchset.

    Wanpeng

      parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-30 18:01 Paolo Bonzini
2020-01-30 18:01 ` [FYI PATCH 1/5] x86/kvm: Be careful not to clear KVM_VCPU_FLUSH_TLB bit Paolo Bonzini
2020-01-30 18:01 ` [FYI PATCH 2/5] x86/kvm: Introduce kvm_(un)map_gfn() Paolo Bonzini
2020-01-30 18:01 ` [FYI PATCH 3/5] x86/kvm: Cache gfn to pfn translation Paolo Bonzini
2020-01-30 18:01 ` [FYI PATCH 4/5] x86/KVM: Make sure KVM_VCPU_FLUSH_TLB flag is not missed Paolo Bonzini
2020-01-30 18:01 ` [FYI PATCH 5/5] x86/KVM: Clean up host's steal time structure Paolo Bonzini
2020-02-01  5:53 ` Wanpeng Li [this message]

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