From: David Gibson <david@gibson.dropbear.id.au> To: Cornelia Huck <cohuck@redhat.com> 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: Mon, 18 Jan 2021 13:59:15 +1100 [thread overview] Message-ID: <20210118025915.GF2089552@yekko.fritz.box> (raw) In-Reply-To: <20210115135425.7fd94aed.cohuck@redhat.com> [-- Attachment #1: Type: text/plain, Size: 2443 bytes --] On Fri, Jan 15, 2021 at 01:54:25PM +0100, Cornelia Huck wrote: > 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/ Fixed, thanks. > > > 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> > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 833 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: David Gibson <david@gibson.dropbear.id.au> To: Cornelia Huck <cohuck@redhat.com> Cc: pair@us.ibm.com, brijesh.singh@amd.com, kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org, frankja@linux.ibm.com, pragyansri.pathi@intel.com, mst@redhat.com, mdroth@linux.vnet.ibm.com, pasic@linux.ibm.com, borntraeger@de.ibm.com, andi.kleen@intel.com, thuth@redhat.com, Eduardo Habkost <ehabkost@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, dgilbert@redhat.com, Greg Kurz <groug@kaod.org>, qemu-s390x@nongnu.org, jun.nakajima@intel.com, berrange@redhat.com, Marcelo Tosatti <mtosatti@redhat.com>, qemu-ppc@nongnu.org, Paolo Bonzini <pbonzini@redhat.com> Subject: Re: [PATCH v7 03/13] sev: Remove false abstraction of flash encryption Date: Mon, 18 Jan 2021 13:59:15 +1100 [thread overview] Message-ID: <20210118025915.GF2089552@yekko.fritz.box> (raw) In-Reply-To: <20210115135425.7fd94aed.cohuck@redhat.com> [-- Attachment #1: Type: text/plain, Size: 2443 bytes --] On Fri, Jan 15, 2021 at 01:54:25PM +0100, Cornelia Huck wrote: > 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/ Fixed, thanks. > > > 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> > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2021-01-18 3:05 UTC|newest] Thread overview: 93+ 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 ` David Gibson 2021-01-13 23:57 ` [PATCH v7 01/13] qom: Allow optional sugar props David Gibson 2021-01-13 23:57 ` David Gibson 2021-01-13 23:58 ` [PATCH v7 02/13] confidential guest support: Introduce new confidential guest support class David Gibson 2021-01-13 23:58 ` David Gibson 2021-01-14 9:34 ` Daniel P. Berrangé 2021-01-14 9:34 ` Daniel P. Berrangé 2021-01-14 10:42 ` David Gibson 2021-01-14 10:42 ` David Gibson 2021-01-18 18:51 ` Dr. David Alan Gilbert 2021-01-18 18:51 ` Dr. David Alan Gilbert 2021-01-21 1:06 ` David Gibson 2021-01-21 1:06 ` David Gibson 2021-01-21 9:08 ` Dr. David Alan Gilbert 2021-01-21 9:08 ` Dr. David Alan Gilbert 2021-01-29 2:32 ` David Gibson 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 2021-01-13 23:58 ` David Gibson 2021-01-15 12:54 ` Cornelia Huck 2021-01-15 12:54 ` Cornelia Huck 2021-01-18 2:59 ` David Gibson [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 2021-01-13 23:58 ` David Gibson 2021-01-15 12:56 ` Cornelia Huck 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 2021-01-13 23:58 ` David Gibson 2021-01-15 13:06 ` Cornelia Huck 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 ` David Gibson 2021-01-13 23:58 ` [PATCH v7 07/13] confidential guest support: Introduce cgs "ready" flag David Gibson 2021-01-13 23:58 ` David Gibson 2021-01-14 8:55 ` Greg Kurz 2021-01-14 8:55 ` Greg Kurz 2021-01-15 13:12 ` Cornelia Huck 2021-01-15 13:12 ` Cornelia Huck 2021-01-18 19:47 ` Dr. David Alan Gilbert 2021-01-18 19:47 ` Dr. David Alan Gilbert 2021-01-19 8:16 ` Cornelia Huck 2021-01-19 8:16 ` Cornelia Huck 2021-02-02 1:41 ` David Gibson 2021-02-02 1:41 ` David Gibson 2021-01-29 6:30 ` David Gibson 2021-01-13 23:58 ` [PATCH v7 08/13] confidential guest support: Move SEV initialization into arch specific code David Gibson 2021-01-13 23:58 ` David Gibson 2021-01-15 13:24 ` Cornelia Huck 2021-01-15 13:24 ` Cornelia Huck 2021-01-18 3:03 ` David Gibson 2021-01-18 3:03 ` David Gibson 2021-01-18 8:03 ` Cornelia Huck 2021-01-18 8:03 ` Cornelia Huck 2021-01-29 3:12 ` David Gibson 2021-01-29 3:12 ` David Gibson 2021-01-13 23:58 ` [PATCH v7 09/13] confidential guest support: Update documentation David Gibson 2021-01-13 23:58 ` David Gibson 2021-01-14 10:07 ` Greg Kurz 2021-01-14 10:07 ` Greg Kurz 2021-01-15 15:36 ` Cornelia Huck 2021-01-15 15:36 ` Cornelia Huck 2021-01-29 2:36 ` David Gibson 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 2021-01-13 23:58 ` David Gibson 2021-01-14 10:39 ` Greg Kurz 2021-01-29 6:23 ` David Gibson 2021-01-15 15:41 ` Cornelia Huck 2021-01-15 15:41 ` Cornelia Huck 2021-01-29 2:43 ` David Gibson 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 ` 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 ` David Gibson 2021-01-13 23:58 ` [PATCH v7 13/13] s390: Recognize confidential-guest-support option David Gibson 2021-01-13 23:58 ` David Gibson 2021-01-14 9:10 ` Christian Borntraeger 2021-01-14 9:10 ` Christian Borntraeger 2021-01-14 9:19 ` Christian Borntraeger 2021-01-14 9:19 ` Christian Borntraeger 2021-01-14 9:24 ` Christian Borntraeger 2021-01-14 9:24 ` Christian Borntraeger 2021-01-15 0:13 ` David Gibson 2021-01-15 0:13 ` David Gibson 2021-01-14 11:45 ` David Gibson 2021-01-14 11:45 ` David Gibson 2021-01-15 16:36 ` Cornelia Huck 2021-01-15 16:36 ` Cornelia Huck 2021-01-18 17:06 ` Christian Borntraeger 2021-01-18 17:06 ` Christian Borntraeger
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