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From: Paolo Bonzini <pbonzini@redhat.com>
To: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>,
	Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Tianyu Lan <ltykernel@gmail.com>,
	"Michael Kelley (LINUX)" <mikelley@microsoft.com>
Subject: Re: "KVM: x86/mmu: Overhaul TDP MMU zapping and flushing" breaks SVM on Hyper-V
Date: Mon, 13 Feb 2023 13:50:12 +0100	[thread overview]
Message-ID: <88a89319-a71e-fa90-0dbb-00cf8a549380@redhat.com> (raw)
In-Reply-To: <9a046de1-8085-3df4-94cd-39bb893c8c9a@linux.microsoft.com>


On 2/13/23 13:44, Jeremi Piotrowski wrote:
> Just built a kernel from that tree, and it displays the same behavior. The problem
> is not that the addresses are wrong, but that the flushes are issued at the wrong
> time now. At least for what "enlightened NPT TLB flush" requires.

It is not clear to me why HvCallFluyshGuestPhysicalAddressSpace or 
HvCallFlushGuestPhysicalAddressList would have stricter requirements 
than a "regular" TLB shootdown using INVEPT.

Can you clarify what you mean by wrong time, preferrably with some kind 
of sequence of events?

That is, something like

CPU 0	Modify EPT from ... to ...
CPU 0	call_rcu() to free page table
CPU 1	... which is invalid because ...
CPU 0	HvCallFlushGuestPhysicalAddressSpace

Paolo


  reply	other threads:[~2023-02-13 12:51 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-10 18:17 Jeremi Piotrowski
2023-02-10 18:45 ` Sean Christopherson
2023-02-13 12:44   ` Jeremi Piotrowski
2023-02-13 12:50     ` Paolo Bonzini [this message]
2023-02-13 18:05       ` Jeremi Piotrowski
2023-02-13 18:26         ` Paolo Bonzini
2023-02-13 17:38 ` Sean Christopherson
2023-02-13 17:49   ` Jeremi Piotrowski
2023-02-13 18:11   ` Paolo Bonzini
2023-02-13 19:11     ` Sean Christopherson
2023-02-13 19:56       ` Paolo Bonzini
2023-02-14 20:27         ` Jeremi Piotrowski
2023-02-15 22:16           ` Sean Christopherson
2023-02-16 14:40             ` Jeremi Piotrowski
2023-02-24 16:17               ` Jeremi Piotrowski
2023-02-24 16:26                 ` Paolo Bonzini

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