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From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ladi Prosek <lprosek@redhat.com>, KVM list <kvm@vger.kernel.org>
Subject: Re: [PATCH 2/4] KVM: nSVM: do not forward NMI window singlestep VM exits to L1
Date: Mon, 19 Jun 2017 19:46:29 +0200	[thread overview]
Message-ID: <20170619174629.GA10318@potion> (raw)
In-Reply-To: <b1132747-75bd-6399-48fb-edf9277e2468@redhat.com>

2017-06-19 19:17+0200, Paolo Bonzini:
> On 19/06/2017 18:17, Radim Krčmář wrote:
> > Right, we only need the single step over IRET and interrupt shadow.
> > 
> > Btw. instead of single-stepping over IRET/interrupt shadow, could we set
> > INTERRUPT_SHADOW in VMCB, inject the NMI, and let it execute?
> > This mechanism would explain why AMD didn't provide a trap for IRET ...
> 
> You mean they didn't provide a trap-like VMEXIT for IRET, only fault-like?

Yes.  SVM has trap-like VM exit, so I didn't understand why it was not
used for IRET.  Forcing the hypervisor to have two VM exits and a clumsy
single-step felt out of place when the rest was designed nicely ...

  reply	other threads:[~2017-06-19 17:46 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-15 11:20 [PATCH 0/4] KVM: SVM: improve NMI window singlestep Ladi Prosek
2017-06-15 11:20 ` [PATCH 1/4] KVM: SVM: introduce disable_nmi_singlestep helper Ladi Prosek
2017-06-15 11:20 ` [PATCH 2/4] KVM: nSVM: do not forward NMI window singlestep VM exits to L1 Ladi Prosek
2017-06-15 12:08   ` Paolo Bonzini
2017-06-16 13:26   ` Radim Krčmář
2017-06-19 12:50     ` Ladi Prosek
2017-06-19 13:05       ` Ladi Prosek
2017-06-19 13:52         ` Paolo Bonzini
2017-06-19 16:17         ` Radim Krčmář
2017-06-19 17:17           ` Paolo Bonzini
2017-06-19 17:46             ` Radim Krčmář [this message]
2017-06-20  7:41           ` Ladi Prosek
2017-06-20 13:01             ` Radim Krčmář
2017-06-15 11:20 ` [PATCH 3/4] KVM: SVM: hide TF/RF flags used by NMI singlestep Ladi Prosek
2017-06-15 12:09   ` Paolo Bonzini
2017-06-15 13:02     ` Ladi Prosek
2017-06-15 13:32       ` Paolo Bonzini
2017-06-15 11:20 ` [PATCH 4/4] KVM: SVM: don't NMI singlestep over event injection Ladi Prosek
2017-06-15 12:05   ` Paolo Bonzini
2017-06-15 12:38     ` Ladi Prosek
2017-06-15 13:21       ` Paolo Bonzini
2017-06-15 12:03 ` [PATCH 0/4] KVM: SVM: improve NMI window singlestep Paolo Bonzini
2017-06-15 12:10   ` Ladi Prosek

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