From: Sean Christopherson <seanjc@google.com>
To: Alexey Kardashevskiy <aik@amd.com>
Cc: kvm@vger.kernel.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Tom Lendacky <thomas.lendacky@amd.com>,
Santosh Shukla <santosh.shukla@amd.com>
Subject: Re: [PATCH kernel 5/9] KVM: SVM/SEV/SEV-ES: Rework intercepts
Date: Fri, 30 Jun 2023 14:49:16 -0700 [thread overview]
Message-ID: <ZJ9N3GMNuKJXc5wQ@google.com> (raw)
In-Reply-To: <20230615063757.3039121-6-aik@amd.com>
On Thu, Jun 15, 2023, Alexey Kardashevskiy wrote:
> @@ -2976,6 +2977,16 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
> svm_set_intercept(svm, TRAP_CR4_WRITE);
> svm_set_intercept(svm, TRAP_CR8_WRITE);
>
> + /*
> + * DR7 access must remain intercepted for an SEV-ES guest to disallow
> + * the guest kernel set up a #DB on memory that's needed to vector a #DB
> + * as otherwise the CPU gets stuck in an infinite #DB loop.
> + */
This isn't correct. Letting the guest configuring breakpoints would be weird
and nonsensical, but it wouldn't lead to infinite #DBs so long as KVM intercepts
#DB.
KVM intercepts DR7 when DebugSwap isn't enabled because otherwise KVM has no way
of context switching DR[0-3] for the guest. At least, I assume that's the case,
AFAICT the APM never actually says what happens with DR[0-3] when DebugSwap is
disabled.
next prev parent reply other threads:[~2023-06-30 21:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-15 6:37 [PATCH kernel 0/9] KVM: SEV: Enable AMD SEV-ES DebugSwap Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 1/9] KVM: SEV: move set_dr_intercepts/clr_dr_intercepts from the header Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 2/9] KVM: SEV: Move SEV's GP_VECTOR intercept setup to SEV Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 3/9] KVM: SVM: Rewrite sev_es_prepare_switch_to_guest()'s comment about swap types Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 4/9] KVM: SEV-ES: explicitly disable debug Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 5/9] KVM: SVM/SEV/SEV-ES: Rework intercepts Alexey Kardashevskiy
2023-06-30 21:49 ` Sean Christopherson [this message]
2023-07-03 2:01 ` Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 6/9] KVM: SEV: Enable data breakpoints in SEV-ES Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 7/9] KVM: SEV-ES: Eliminate #DB intercept when DebugSwap enabled Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 8/9] KVM: SVM: Don't defer NMI unblocking until next exit for SEV-ES guests Alexey Kardashevskiy
2023-06-15 6:37 ` [PATCH kernel 9/9] KVM: SVM: Don't try to pointlessly single-step SEV-ES guests for NMI window Alexey Kardashevskiy
2023-06-15 7:13 ` [PATCH kernel 0/9 v6] KVM: SEV: Enable AMD SEV-ES DebugSwap Alexey Kardashevskiy
2023-06-23 1:35 ` Alexey Kardashevskiy
2023-06-23 14:19 ` Sean Christopherson
2023-06-30 2:08 ` Alexey Kardashevskiy
2023-06-30 21:52 ` Sean Christopherson
2023-07-20 19:01 ` Alexey Kardashevskiy
2023-07-28 23:49 ` [PATCH kernel 0/9] " Sean Christopherson
2023-07-29 1:57 ` Alexey Kardashevskiy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZJ9N3GMNuKJXc5wQ@google.com \
--to=seanjc@google.com \
--cc=aik@amd.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=santosh.shukla@amd.com \
--cc=thomas.lendacky@amd.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox