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From: Paolo Bonzini <pbonzini@redhat.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	Richard Henderson <rth@twiddle.net>,
	Connor Kuehl <ckuehl@redhat.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Jiri Slaby <jslaby@suse.cz>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Aurelien Jarno <aurelien@aurel32.net>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	David Hildenbrand <david@redhat.com>
Subject: Re: [PATCH v4 4/6] sev/i386: Don't allow a system reset under an SEV-ES guest
Date: Tue, 26 Jan 2021 17:16:49 +0100	[thread overview]
Message-ID: <66a57543-a98a-d62e-5213-e203efda5dce@redhat.com> (raw)
In-Reply-To: <c40de4c1bf4d14d60942fba86b2827543c19374a.1601060620.git.thomas.lendacky@amd.com>

On 25/09/20 21:03, Tom Lendacky wrote:
> 
>  {
> -    if (no_reboot && reason != SHUTDOWN_CAUSE_SUBSYSTEM_RESET) {
> +    if (!cpus_are_resettable()) {
> +        error_report("cpus are not resettable, terminating");
> +        shutdown_requested = reason;
> +    } else if (no_reboot && reason != SHUTDOWN_CAUSE_SUBSYSTEM_RESET) {

The error should not be emitted if "no_reboot && reason != 
SHUTDOWN_CAUSE_SUBSYSTEM_RESET" (the condition has changed a bit in 
latest QEMU but the idea is the same).

This is because whoever invoked QEMU could already know about this 
SEV-ES limitation, and use -no-reboot (aka -action reset=shutdown in 
6.0) in order to change the forbidden warm reset into a shutdown+restart 
cold reset.

Paolo


WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Eduardo Habkost <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Connor Kuehl <ckuehl@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	David Gibson <david@gibson.dropbear.id.au>,
	Jiri Slaby <jslaby@suse.cz>,
	Aurelien Jarno <aurelien@aurel32.net>,
	Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH v4 4/6] sev/i386: Don't allow a system reset under an SEV-ES guest
Date: Tue, 26 Jan 2021 17:16:49 +0100	[thread overview]
Message-ID: <66a57543-a98a-d62e-5213-e203efda5dce@redhat.com> (raw)
In-Reply-To: <c40de4c1bf4d14d60942fba86b2827543c19374a.1601060620.git.thomas.lendacky@amd.com>

On 25/09/20 21:03, Tom Lendacky wrote:
> 
>  {
> -    if (no_reboot && reason != SHUTDOWN_CAUSE_SUBSYSTEM_RESET) {
> +    if (!cpus_are_resettable()) {
> +        error_report("cpus are not resettable, terminating");
> +        shutdown_requested = reason;
> +    } else if (no_reboot && reason != SHUTDOWN_CAUSE_SUBSYSTEM_RESET) {

The error should not be emitted if "no_reboot && reason != 
SHUTDOWN_CAUSE_SUBSYSTEM_RESET" (the condition has changed a bit in 
latest QEMU but the idea is the same).

This is because whoever invoked QEMU could already know about this 
SEV-ES limitation, and use -no-reboot (aka -action reset=shutdown in 
6.0) in order to change the forbidden warm reset into a shutdown+restart 
cold reset.

Paolo



  reply	other threads:[~2021-01-26 16:18 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-25 19:03 [PATCH v4 0/6] Qemu SEV-ES guest support Tom Lendacky
2020-09-25 19:03 ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 1/6] sev/i386: Add initial support for SEV-ES Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 2/6] sev/i386: Require in-kernel irqchip support for SEV-ES guests Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 3/6] sev/i386: Allow AP booting under SEV-ES Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 4/6] sev/i386: Don't allow a system reset under an SEV-ES guest Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2021-01-26 16:16   ` Paolo Bonzini [this message]
2021-01-26 16:16     ` Paolo Bonzini
2021-01-26 16:24     ` Tom Lendacky
2021-01-26 16:24       ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 5/6] kvm/i386: Use a per-VM check for SMM capability Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2020-09-25 19:03 ` [PATCH v4 6/6] sev/i386: Enable an SEV-ES guest based on SEV policy Tom Lendacky
2020-09-25 19:03   ` Tom Lendacky
2020-09-25 19:08 ` [PATCH v4 0/6] Qemu SEV-ES guest support Tom Lendacky
2020-09-25 19:08   ` Tom Lendacky
2020-09-25 22:57 ` no-reply
2020-09-25 22:57   ` no-reply
2021-01-26 16:21 ` Paolo Bonzini
2021-01-26 16:21   ` Paolo Bonzini
2021-01-26 16:49   ` Tom Lendacky
2021-01-26 16:49     ` Tom Lendacky
2021-01-26 17:13     ` Tom Lendacky
2021-01-26 17:13       ` Tom Lendacky
2021-01-26 17:18       ` Paolo Bonzini
2021-01-26 17:18         ` Paolo Bonzini

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