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From: Sean Christopherson <seanjc@google.com>
To: Jim Mattson <jmattson@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.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>
Subject: Re: [PATCH v2 05/21] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag
Date: Thu, 7 Jul 2022 17:14:40 +0000	[thread overview]
Message-ID: <YscUgGElDEPIkIEo@google.com> (raw)
In-Reply-To: <CALMp9eSH1O8keAVxZzfdvV1vu0AJBhaXVUfkSgYgCPOoSB5=Jw@mail.gmail.com>

On Wed, Jul 06, 2022, Jim Mattson wrote:
> On Tue, Jun 14, 2022 at 1:47 PM Sean Christopherson <seanjc@google.com> wrote:
> >
> > Service TSS T-flag #DBs prior to pending MTFs, as such #DBs are higher
> > priority than MTF.  KVM itself doesn't emulate TSS #DBs, and any such
> 
> Is there a KVM erratum for that?

Nope, just this hilarious TODO:

	/*
	 * TODO: What about debug traps on tss switch?
	 *       Are we supposed to inject them and update dr6?
	 */

> > exceptions injected from L1 will be handled by hardware (or morphed to
> > a fault-like exception if injection fails), but theoretically userspace
> > could pend a TSS T-flag #DB in conjunction with a pending MTF.
> >
> > Note, there's no known use case this fixes, it's purely to be technically
> > correct with respect to Intel's SDM.
> 
> A test would be nice. :-)

LOL, yeah, but ensuring userspace-injected TSS T-bit #DBs work isn't exactly on
my list of top 100 things to look at.

  reply	other threads:[~2022-07-07 17:14 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-14 20:47 [PATCH v2 00/21] KVM: x86: Event/exception fixes and cleanups Sean Christopherson
2022-06-14 20:47 ` [PATCH v2 01/21] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit" Sean Christopherson
2022-06-16 23:47   ` Jim Mattson
2022-07-06 11:40   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 02/21] KVM: VMX: Drop bits 31:16 when shoving exception error code into VMCS Sean Christopherson
2022-07-06 11:43   ` Maxim Levitsky
2022-07-06 16:12     ` Sean Christopherson
2022-07-06 18:50       ` Maxim Levitsky
2022-07-06 20:02   ` Jim Mattson
2022-06-14 20:47 ` [PATCH v2 03/21] KVM: x86: Don't check for code breakpoints when emulating on exception Sean Christopherson
2022-07-06 11:43   ` Maxim Levitsky
2022-07-06 22:17   ` Jim Mattson
2022-06-14 20:47 ` [PATCH v2 04/21] KVM: nVMX: Treat General Detect #DB (DR7.GD=1) as fault-like Sean Christopherson
2022-07-06 11:45   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 05/21] KVM: nVMX: Prioritize TSS T-flag #DBs over Monitor Trap Flag Sean Christopherson
2022-07-06 11:57   ` Maxim Levitsky
2022-07-06 23:51   ` Jim Mattson
2022-07-07 17:14     ` Sean Christopherson [this message]
2022-06-14 20:47 ` [PATCH v2 06/21] KVM: x86: Treat #DBs from the emulator as fault-like (code and DR7.GD=1) Sean Christopherson
2022-07-06 11:57   ` Maxim Levitsky
2022-07-06 23:55   ` Jim Mattson
2022-07-07 17:19     ` Sean Christopherson
2022-06-14 20:47 ` [PATCH v2 07/21] KVM: x86: Use DR7_GD macro instead of open coding check in emulator Sean Christopherson
2022-07-06 11:58   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 08/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS Sean Christopherson
2022-07-06 11:59   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 09/21] KVM: nVMX: Unconditionally clear mtf_pending on nested VM-Exit Sean Christopherson
2022-07-06 12:00   ` Maxim Levitsky
2022-07-06 16:45     ` Sean Christopherson
2022-07-06 20:03       ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 10/21] KVM: VMX: Inject #PF on ENCLS as "emulated" #PF Sean Christopherson
2022-07-06 12:00   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 11/21] KVM: x86: Rename kvm_x86_ops.queue_exception to inject_exception Sean Christopherson
2022-07-06 12:01   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 12/21] KVM: x86: Make kvm_queued_exception a properly named, visible struct Sean Christopherson
2022-07-06 12:02   ` Maxim Levitsky
2022-07-18 13:07   ` Maxim Levitsky
2022-07-18 13:10     ` Maxim Levitsky
2022-07-18 15:40       ` Sean Christopherson
2022-06-14 20:47 ` [PATCH v2 13/21] KVM: x86: Formalize blocking of nested pending exceptions Sean Christopherson
2022-07-06 12:04   ` Maxim Levitsky
2022-07-06 17:36     ` Sean Christopherson
2022-07-06 20:03       ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 14/21] KVM: x86: Use kvm_queue_exception_e() to queue #DF Sean Christopherson
2022-07-06 12:04   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 15/21] KVM: x86: Hoist nested event checks above event injection logic Sean Christopherson
2022-07-06 12:05   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 16/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit Sean Christopherson
2022-07-06 12:05   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 17/21] KVM: x86: Morph pending exceptions to pending VM-Exits at queue time Sean Christopherson
2022-07-06 12:15   ` Maxim Levitsky
2022-07-07  1:24     ` Sean Christopherson
2022-07-10 15:56       ` Maxim Levitsky
2022-07-11 15:22         ` Sean Christopherson
2022-06-14 20:47 ` [PATCH v2 18/21] KVM: x86: Treat pending TRIPLE_FAULT requests as pending exceptions Sean Christopherson
2022-07-06 12:16   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 19/21] KVM: VMX: Update MTF and ICEBP comments to document KVM's subtle behavior Sean Christopherson
2022-06-14 20:47 ` [PATCH v2 20/21] KVM: selftests: Use uapi header to get VMX and SVM exit reasons/codes Sean Christopherson
2022-07-06 12:16   ` Maxim Levitsky
2022-06-14 20:47 ` [PATCH v2 21/21] KVM: selftests: Add an x86-only test to verify nested exception queueing Sean Christopherson
2022-07-06 12:17   ` Maxim Levitsky
2022-06-16 13:16 ` [PATCH v2 00/21] KVM: x86: Event/exception fixes and cleanups Maxim Levitsky
2022-06-29 11:16 ` Maxim Levitsky
2022-06-29 13:42   ` Jim Mattson
2022-06-30  8:22     ` Maxim Levitsky
2022-06-30 12:17       ` Jim Mattson
2022-06-30 13:10         ` Maxim Levitsky
2022-06-30 16:28       ` Jim Mattson
2022-07-01  7:37         ` Maxim Levitsky
2022-07-06 11:54     ` Maxim Levitsky
2022-07-06 17:13       ` Jim Mattson
2022-07-06 17:52         ` Sean Christopherson
2022-07-06 20:03           ` Maxim Levitsky
2022-07-06 20:11           ` Jim Mattson
2022-07-10 15:58             ` Maxim Levitsky
2022-06-29 15:53   ` Jim Mattson
2022-06-30  8:24     ` Maxim Levitsky
2022-06-30 12:20       ` Jim Mattson

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