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From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups
Date: Fri, 11 Mar 2022 17:30:03 +0100	[thread overview]
Message-ID: <d04e096a-b12e-91e2-204e-b3643a62d705@maciej.szmigiero.name> (raw)
In-Reply-To: <20220311032801.3467418-1-seanjc@google.com>


Hi Sean,

On 11.03.2022 04:27, Sean Christopherson wrote:
> The main goal of this series is to fix KVM's longstanding bug of not
> honoring L1's exception intercepts wants when handling an exception that
> occurs during delivery of a different exception.  E.g. if L0 and L1 are
> using shadow paging, and L2 hits a #PF, and then hits another #PF while
> vectoring the first #PF due to _L1_ not having a shadow page for the IDT,
> KVM needs to check L1's intercepts before morphing the #PF => #PF => #DF
> so that the #PF is routed to L1, not injected into L2 as a #DF.
> 
> nVMX has hacked around the bug for years by overriding the #PF injector
> for shadow paging to go straight to VM-Exit, and nSVM has started doing
> the same.  The hacks mostly work, but they're incomplete, confusing, and
> lead to other hacky code, e.g. bailing from the emulator because #PF
> injection forced a VM-Exit and suddenly KVM is back in L1.

Looks like we were working on similar KVM area recently [1].

It look like parts of our patch sets touch the same code.
Since your patch set is much bigger and comprehensive I will base mine on
top of yours once there are no more incoming review comments for your
patch set (in other words, once it is in its final form).

Thanks,
Maciej

[1]: https://lore.kernel.org/kvm/cover.1646944472.git.maciej.szmigiero@oracle.com/

  parent reply	other threads:[~2022-03-11 16:30 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-11  3:27 [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-03-11  3:27 ` [PATCH 01/21] KVM: x86: Return immediately from x86_emulate_instruction() on code #DB Sean Christopherson
2022-03-11  3:27 ` [PATCH 02/21] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-03-11  3:27 ` [PATCH 03/21] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-03-11  3:27 ` [PATCH 04/21] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-03-11  3:27 ` [PATCH 05/21] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-03-11  3:27 ` [PATCH 06/21] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-03-11  3:27 ` [PATCH 07/21] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-03-11  3:27 ` [PATCH 08/21] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-03-11  3:27 ` [PATCH 09/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-03-11  3:27 ` [PATCH 10/21] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-03-11  3:27 ` [PATCH 11/21] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-03-11  3:27 ` [PATCH 12/21] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-03-11  3:27 ` [PATCH 13/21] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-03-11  3:27 ` [PATCH 14/21] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-03-11  3:27 ` [PATCH 15/21] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-03-11  3:27 ` [PATCH 16/21] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-03-11  3:27 ` [PATCH 17/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-03-11  3:27 ` [PATCH 18/21] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-03-11  3:27 ` [PATCH 19/21] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-03-11  3:28 ` [PATCH 20/21] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-03-11  3:28 ` [PATCH 21/21] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-03-11 16:30 ` Maciej S. Szmigiero [this message]
2022-03-13  9:22 ` [PATCH 00/21] KVM: x86: Event/exception fixes and cleanups Maxim Levitsky
2022-03-24 21:31   ` Sean Christopherson
2022-03-25 21:25     ` Maciej S. Szmigiero
2022-03-25 23:02       ` Sean Christopherson
2022-03-26  0:21         ` Maciej S. Szmigiero
2022-03-27 15:06     ` Maxim Levitsky
2022-03-28 17:50       ` Sean Christopherson
2022-03-29 10:45         ` Maxim Levitsky
2022-03-29 15:43           ` Sean Christopherson

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