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From: Paolo Bonzini <pbonzini@redhat.com>
To: Dov Murik <dovmurik@linux.ibm.com>
Cc: "Tom Lendacky" <thomas.lendacky@amd.com>,
	"Ashish Kalra" <ashish.kalra@amd.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Connor Kuehl" <ckuehl@redhat.com>,
	"Laszlo Ersek" <lersek@redhat.com>,
	"James Bottomley" <jejb@linux.ibm.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	"Hubertus Franke" <frankeh@us.ibm.com>,
	"Tobin Feldman-Fitzthum" <tobin@linux.ibm.com>,
	"Jim Cadden" <jcadden@ibm.com>,
	"Brijesh Singh" <brijesh.singh@amd.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: Re: [PATCH v4 0/2] x86/sev: Measured Linux SEV guest with kernel/initrd/cmdline
Date: Mon, 4 Oct 2021 10:03:02 +0200	[thread overview]
Message-ID: <CABgObfb3VOSav+pdwC5_xrCeM5S32B2XV02L7H7DWx+9Gi8u_g@mail.gmail.com> (raw)
In-Reply-To: <20210930054915.13252-1-dovmurik@linux.ibm.com>

Queued, thanks.  However, it would be nice to have a documentation of
all our SEV firmware interfaces somewhere in docs/specs/.

Paolo

On Thu, Sep 30, 2021 at 7:49 AM Dov Murik <dovmurik@linux.ibm.com> wrote:
>
> Currently booting with -kernel/-initrd/-append is not supported in SEV
> confidential guests, because the content of these blobs is not measured
> and therefore not trusted by the SEV guest.
>
> However, in some cases the kernel, initrd, and cmdline are not secret
> but should not be modified by the host.  In such a case, we want to
> verify inside the trusted VM that the kernel, initrd, and cmdline are
> indeed the ones expected by the Guest Owner, and only if that is the
> case go on and boot them up (removing the need for grub inside OVMF in
> that mode).
>
> To support that, OVMF adds a special area for hashes of
> kernel/initrd/cmdline; that area is expected to be filled by QEMU and
> encrypted as part of the initial SEV guest launch.  This in turn makes
> the hashes part of the AMD PSP measured content, and OVMF can trust
> these inputs if they match the hashes.
>
> This series adds an SEV function to generate the table of hashes for
> OVMF and encrypt it (patch 1/2), and calls this function if SEV is
> enabled when the kernel/initrd/cmdline are prepared (patch 2/2).
>
> Corresponding OVMF support [1] is already available in edk2 (patch series
> "Measured SEV boot with kernel/initrd/cmdline").
>
> [1] https://edk2.groups.io/g/devel/message/78250
>
> ---
>
> v4 changes:
>  - struct and variable renames (KernelLoaderContext -> SevKernelLoaderContext,
>    kernel_loader_context -> sev_load_ctx).
>
> v3 resend: https://lore.kernel.org/qemu-devel/20210825073538.959525-1-dovmurik@linux.ibm.com/
> v3: https://lore.kernel.org/qemu-devel/20210624102040.2015280-1-dovmurik@linux.ibm.com/
> v3 changes:
>  - initrd hash is now mandatory; if no -initrd is passed, calculate the
>    hash of the empty buffer.  This is now aligned with the OVMF
>    behaviour which verifies the empty initrd (correctly).
>  - make SevHashTable entries fixed: 3 entries for cmdline, initrd, and kernel.
>  - in sev_add_kernel_loader_hashes: first calculate all the hashes, only then
>    fill-in the hashes table in the guest's memory.
>  - Use g_assert_not_reached in sev-stub.c.
>  - Use QEMU_PACKED attribute for structs.
>  - Use QemuUUID type for guids.
>  - in sev_add_kernel_loader_hashes: use ARRAY_SIZE(iov) instead of literal 2.
>
> v2: https://lore.kernel.org/qemu-devel/20210621190553.1763020-1-dovmurik@linux.ibm.com/
> v2 changes:
>  - Extract main functionality to sev.c (with empty stub in sev-stub.c)
>  - Use sev_enabled() instead of machine->cgs->ready to detect SEV guest
>  - Coding style changes
>
> v1: https://lore.kernel.org/qemu-devel/20210525065931.1628554-1-dovmurik@linux.ibm.com/
>
>
> Dov Murik (2):
>   sev/i386: Introduce sev_add_kernel_loader_hashes for measured linux
>     boot
>   x86/sev: generate SEV kernel loader hashes in x86_load_linux
>
>  target/i386/sev_i386.h |  12 ++++
>  hw/i386/x86.c          |  25 +++++++-
>  target/i386/sev-stub.c |   5 ++
>  target/i386/sev.c      | 137 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 178 insertions(+), 1 deletion(-)
>
> --
> 2.25.1
>



  parent reply	other threads:[~2021-10-04  8:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-30  5:49 Dov Murik
2021-09-30  5:49 ` [PATCH v4 1/2] sev/i386: Introduce sev_add_kernel_loader_hashes for measured linux boot Dov Murik
2021-09-30  8:32   ` Daniel P. Berrangé
2021-09-30 10:13     ` Dov Murik
2021-10-18 18:02   ` Tom Lendacky
2021-10-19  6:18     ` Dov Murik
2021-10-20 15:26       ` Tom Lendacky
2021-10-27 19:43         ` Brijesh Singh
2021-10-28  8:41           ` Dov Murik
2021-11-01 10:28             ` Dov Murik
2021-09-30  5:49 ` [PATCH v4 2/2] x86/sev: generate SEV kernel loader hashes in x86_load_linux Dov Murik
2021-10-04  8:03 ` Paolo Bonzini [this message]
2021-10-04 17:23   ` [PATCH v4 0/2] x86/sev: Measured Linux SEV guest with kernel/initrd/cmdline Dov Murik

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