From: Cornelia Huck <cohuck@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: brijesh.singh@amd.com, pair@us.ibm.com, dgilbert@redhat.com,
pasic@linux.ibm.com, qemu-devel@nongnu.org,
Richard Henderson <richard.henderson@linaro.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
David Hildenbrand <david@redhat.com>,
borntraeger@de.ibm.com,
Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
mst@redhat.com, jun.nakajima@intel.com, thuth@redhat.com,
pragyansri.pathi@intel.com, kvm@vger.kernel.org,
Eduardo Habkost <ehabkost@redhat.com>,
qemu-s390x@nongnu.org, qemu-ppc@nongnu.org,
frankja@linux.ibm.com, Greg Kurz <groug@kaod.org>,
mdroth@linux.vnet.ibm.com, berrange@redhat.com,
andi.kleen@intel.com
Subject: Re: [PATCH v7 03/13] sev: Remove false abstraction of flash encryption
Date: Fri, 15 Jan 2021 13:54:25 +0100 [thread overview]
Message-ID: <20210115135425.7fd94aed.cohuck@redhat.com> (raw)
In-Reply-To: <20210113235811.1909610-4-david@gibson.dropbear.id.au>
On Thu, 14 Jan 2021 10:58:01 +1100
David Gibson <david@gibson.dropbear.id.au> wrote:
> When AMD's SEV memory encryption is in use, flash memory banks (which are
> initialed by pc_system_flash_map()) need to be encrypted with the guest's
> key, so that the guest can read them.
>
> That's abstracted via the kvm_memcrypt_encrypt_data() callback in the KVM
> state.. except, that it doesn't really abstract much at all.
>
> For starters, the only called is in code specific to the 'pc' family of
s/called/call site/
> machine types, so it's obviously specific to those and to x86 to begin
> with. But it makes a bunch of further assumptions that need not be true
> about an arbitrary confidential guest system based on memory encryption,
> let alone one based on other mechanisms:
>
> * it assumes that the flash memory is defined to be encrypted with the
> guest key, rather than being shared with hypervisor
> * it assumes that that hypervisor has some mechanism to encrypt data into
> the guest, even though it can't decrypt it out, since that's the whole
> point
> * the interface assumes that this encrypt can be done in place, which
> implies that the hypervisor can write into a confidential guests's
> memory, even if what it writes isn't meaningful
>
> So really, this "abstraction" is actually pretty specific to the way SEV
> works. So, this patch removes it and instead has the PC flash
> initialization code call into a SEV specific callback.
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> accel/kvm/kvm-all.c | 31 ++-----------------------------
> accel/kvm/sev-stub.c | 9 ++-------
> accel/stubs/kvm-stub.c | 10 ----------
> hw/i386/pc_sysfw.c | 17 ++++++-----------
> include/sysemu/kvm.h | 16 ----------------
> include/sysemu/sev.h | 4 ++--
> target/i386/sev-stub.c | 5 +++++
> target/i386/sev.c | 24 ++++++++++++++----------
> 8 files changed, 31 insertions(+), 85 deletions(-)
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
next prev parent reply other threads:[~2021-01-15 12:56 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 23:57 [PATCH v7 00/13] Generalize memory encryption models David Gibson
2021-01-13 23:57 ` [PATCH v7 01/13] qom: Allow optional sugar props David Gibson
2021-01-13 23:58 ` [PATCH v7 02/13] confidential guest support: Introduce new confidential guest support class David Gibson
2021-01-14 9:34 ` Daniel P. Berrangé
2021-01-14 10:42 ` David Gibson
2021-01-18 18:51 ` Dr. David Alan Gilbert
2021-01-21 1:06 ` David Gibson
2021-01-21 9:08 ` Dr. David Alan Gilbert
2021-01-29 2:32 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 03/13] sev: Remove false abstraction of flash encryption David Gibson
2021-01-15 12:54 ` Cornelia Huck [this message]
2021-01-18 2:59 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 04/13] confidential guest support: Move side effect out of machine_set_memory_encryption() David Gibson
2021-01-15 12:56 ` Cornelia Huck
2021-01-13 23:58 ` [PATCH v7 05/13] confidential guest support: Rework the "memory-encryption" property David Gibson
2021-01-15 13:06 ` Cornelia Huck
2021-01-13 23:58 ` [PATCH v7 06/13] sev: Add Error ** to sev_kvm_init() David Gibson
2021-01-13 23:58 ` [PATCH v7 07/13] confidential guest support: Introduce cgs "ready" flag David Gibson
2021-01-14 8:55 ` Greg Kurz
2021-01-15 13:12 ` Cornelia Huck
2021-01-18 19:47 ` Dr. David Alan Gilbert
2021-01-19 8:16 ` Cornelia Huck
2021-02-02 1:41 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 08/13] confidential guest support: Move SEV initialization into arch specific code David Gibson
2021-01-15 13:24 ` Cornelia Huck
2021-01-18 3:03 ` David Gibson
2021-01-18 8:03 ` Cornelia Huck
2021-01-29 3:12 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 09/13] confidential guest support: Update documentation David Gibson
2021-01-14 10:07 ` Greg Kurz
2021-01-15 15:36 ` Cornelia Huck
2021-01-29 2:36 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 10/13] spapr: Add PEF based confidential guest support David Gibson
2021-01-15 15:41 ` Cornelia Huck
2021-01-29 2:43 ` David Gibson
2021-01-13 23:58 ` [PATCH v7 11/13] spapr: PEF: prevent migration David Gibson
2021-01-13 23:58 ` [PATCH v7 12/13] confidential guest support: Alter virtio default properties for protected guests David Gibson
2021-01-13 23:58 ` [PATCH v7 13/13] s390: Recognize confidential-guest-support option David Gibson
2021-01-14 9:10 ` Christian Borntraeger
2021-01-14 9:19 ` Christian Borntraeger
2021-01-14 9:24 ` Christian Borntraeger
2021-01-15 0:13 ` David Gibson
2021-01-14 11:45 ` David Gibson
2021-01-15 16:36 ` Cornelia Huck
2021-01-18 17:06 ` Christian Borntraeger
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