From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>,
Ashish Kalra <Ashish.Kalra@amd.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Eduardo Habkost <ehabkost@redhat.com>,
kvm-devel <kvm@vger.kernel.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Markus Armbruster <armbru@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
ssg.sos.patches@amd.com, Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH 01/11] memattrs: add debug attribute
Date: Tue, 1 Dec 2020 11:50:47 +0000 [thread overview]
Message-ID: <20201201115047.GA15055@work-vm> (raw)
In-Reply-To: <CAFEAcA8eiyzUbHXQip1sT_TrT+Mfv-WG8cSMmM-w_eOFShAMzQ@mail.gmail.com>
* Peter Maydell (peter.maydell@linaro.org) wrote:
> On Mon, 16 Nov 2020 at 19:28, Ashish Kalra <Ashish.Kalra@amd.com> wrote:
> >
> > From: Brijesh Singh <brijesh.singh@amd.com>
> >
> > From: Brijesh Singh <brijesh.singh@amd.com>
> >
> > Extend the MemTxAttrs to include a 'debug' flag. The flag can be used as
> > general indicator that operation was triggered by the debugger.
> >
> > A subsequent patch will set the debug=1 when issuing a memory access
> > from the gdbstub or HMP commands. This is a prerequisite to support
> > debugging an encrypted guest. When a request with debug=1 is seen, the
> > encryption APIs will be used to access the guest memory.
>
> So, what counts as "debug" here, and why are debug requests
> special? If "debug=1" means "can actually get at the guest memory",
> why wouldn't every device model want to use it?
SEV has a flag that the guest-owner can set on a VM to enable debug;
it's rare for it to be enabled; so it's not suitable for use by normal
devices. It's only there for debug if the guest owner allows you to.
Dave
> thanks
> -- PMM
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2020-12-01 11:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 18:48 [PATCH 00/11] Add QEMU debug support for SEV guests Ashish Kalra
2020-11-16 18:48 ` [PATCH 01/11] memattrs: add debug attribute Ashish Kalra
2020-12-01 11:03 ` Dr. David Alan Gilbert
2020-12-01 11:43 ` Peter Maydell
2020-12-01 11:50 ` Dr. David Alan Gilbert [this message]
2020-12-01 11:56 ` Peter Maydell
2020-12-01 18:57 ` Dr. David Alan Gilbert
2020-11-16 18:49 ` [PATCH 02/11] exec: Add new MemoryDebugOps Ashish Kalra
2020-12-01 11:37 ` Dr. David Alan Gilbert
2020-12-01 11:48 ` Peter Maydell
2020-12-01 14:27 ` Ashish Kalra
2020-12-01 14:38 ` Peter Maydell
2020-12-01 14:49 ` Ashish Kalra
2020-11-16 18:49 ` [PATCH 03/11] exec: add ram_debug_ops support Ashish Kalra
2020-12-01 12:08 ` Peter Maydell
2020-12-01 14:43 ` Ashish Kalra
2020-11-16 18:50 ` [PATCH 04/11] exec: Add address_space_read and address_space_write debug helpers Ashish Kalra
2020-11-16 18:51 ` [PATCH 05/11] exec: add debug version of physical memory read and write API Ashish Kalra
2020-11-24 5:42 ` Dov Murik
2020-11-16 18:51 ` [PATCH 06/11] monitor/i386: use debug APIs when accessing guest memory Ashish Kalra
2020-12-01 11:54 ` Peter Maydell
2020-12-01 12:05 ` Peter Maydell
2020-11-16 18:51 ` [PATCH 07/11] kvm: introduce debug memory encryption API Ashish Kalra
2020-11-16 18:52 ` [PATCH 08/11] sev/i386: add debug encrypt and decrypt commands Ashish Kalra
2020-11-16 18:52 ` [PATCH 09/11] hw/i386: set ram_debug_ops when memory encryption is enabled Ashish Kalra
2020-11-16 18:52 ` [PATCH 10/11] sev/i386: add SEV specific MemoryDebugOps Ashish Kalra
2020-11-16 18:53 ` [PATCH 11/11] target/i386: clear C-bit when walking SEV guest page table Ashish Kalra
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