From: Greg Kurz <groug@kaod.org> To: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: pair@us.ibm.com, brijesh.singh@amd.com, frankja@linux.ibm.com, kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>, "Cornelia Huck" <cohuck@redhat.com>, "David Hildenbrand" <david@redhat.com>, qemu-devel@nongnu.org, ehabkost@redhat.com, mdroth@linux.vnet.ibm.com, pasic@linux.ibm.com, "Christian Borntraeger" <borntraeger@de.ibm.com>, qemu-s390x@nongnu.org, qemu-ppc@nongnu.org, marcel.apfelbaum@gmail.com, pbonzini@redhat.com, "Thomas Huth" <thuth@redhat.com>, "Daniel P.Berrangé" <berrange@redhat.com>, "Richard Henderson" <rth@twiddle.net>, "David Gibson" <david@gibson.dropbear.id.au> Subject: Re: [for-5.2 v4 09/10] host trust limitation: Alter virtio default properties for protected guests Date: Thu, 13 Aug 2020 10:19:06 +0200 [thread overview] Message-ID: <20200813101906.799efe55@bahia.lan> (raw) In-Reply-To: <20200813094356.651f323c@bahia.lan> On Thu, 13 Aug 2020 09:43:56 +0200 Greg Kurz <groug@kaod.org> wrote: > On Mon, 27 Jul 2020 16:05:14 +0100 > "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote: > > > * David Gibson (david@gibson.dropbear.id.au) wrote: > > > The default behaviour for virtio devices is not to use the platforms normal > > > DMA paths, but instead to use the fact that it's running in a hypervisor > > > to directly access guest memory. That doesn't work if the guest's memory > > > is protected from hypervisor access, such as with AMD's SEV or POWER's PEF. > > > > > > So, if a host trust limitation mechanism is enabled, then apply the > > > iommu_platform=on option so it will go through normal DMA mechanisms. > > > Those will presumably have some way of marking memory as shared with the > > > hypervisor or hardware so that DMA will work. > > > > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > > > > Good, it's just too easy to forget them at the moment and get hopelessly > > confused. > > > > > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > > > > --- > > > hw/core/machine.c | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > index b599b0ba65..2a723bf07b 100644 > > > --- a/hw/core/machine.c > > > +++ b/hw/core/machine.c > > > @@ -28,6 +28,8 @@ > > > #include "hw/mem/nvdimm.h" > > > #include "migration/vmstate.h" > > > #include "exec/host-trust-limitation.h" > > > +#include "hw/virtio/virtio.h" > > > +#include "hw/virtio/virtio-pci.h" > > > > > > GlobalProperty hw_compat_5_0[] = { > > > { "virtio-balloon-device", "page-poison", "false" }, > > > @@ -1161,6 +1163,15 @@ void machine_run_board_init(MachineState *machine) > > > * areas. > > > */ > > > machine_set_mem_merge(OBJECT(machine), false, &error_abort); > > > + > > > + /* > > > + * Virtio devices can't count on directly accessing guest > > > + * memory, so they need iommu_platform=on to use normal DMA > > > + * mechanisms. That requires disabling legacy virtio support > > > + * for virtio pci devices > > > + */ > > > + object_register_sugar_prop(TYPE_VIRTIO_PCI, "disable-legacy", "on"); > > What about non-transitional devices (eg. vhost-user-fs-pci) ? They don't know > about "disable-legacy" since they don't need it. > Ok, it looks like we should add a bool argument to object_register_sugar_prop() that sets the .optional field of GlobalProperty. > > > + object_register_sugar_prop(TYPE_VIRTIO_DEVICE, "iommu_platform", "on"); > > > } > > > > > > machine_class->init(machine); > > > -- > > > 2.26.2 > > > > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > >
WARNING: multiple messages have this Message-ID (diff)
From: Greg Kurz <groug@kaod.org> To: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: pair@us.ibm.com, brijesh.singh@amd.com, frankja@linux.ibm.com, kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>, "David Gibson" <david@gibson.dropbear.id.au>, "Cornelia Huck" <cohuck@redhat.com>, "David Hildenbrand" <david@redhat.com>, qemu-devel@nongnu.org, mdroth@linux.vnet.ibm.com, pasic@linux.ibm.com, "Christian Borntraeger" <borntraeger@de.ibm.com>, qemu-s390x@nongnu.org, qemu-ppc@nongnu.org, "Daniel P.Berrangé" <berrange@redhat.com>, "Thomas Huth" <thuth@redhat.com>, pbonzini@redhat.com, "Richard Henderson" <rth@twiddle.net>, ehabkost@redhat.com Subject: Re: [for-5.2 v4 09/10] host trust limitation: Alter virtio default properties for protected guests Date: Thu, 13 Aug 2020 10:19:06 +0200 [thread overview] Message-ID: <20200813101906.799efe55@bahia.lan> (raw) In-Reply-To: <20200813094356.651f323c@bahia.lan> On Thu, 13 Aug 2020 09:43:56 +0200 Greg Kurz <groug@kaod.org> wrote: > On Mon, 27 Jul 2020 16:05:14 +0100 > "Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote: > > > * David Gibson (david@gibson.dropbear.id.au) wrote: > > > The default behaviour for virtio devices is not to use the platforms normal > > > DMA paths, but instead to use the fact that it's running in a hypervisor > > > to directly access guest memory. That doesn't work if the guest's memory > > > is protected from hypervisor access, such as with AMD's SEV or POWER's PEF. > > > > > > So, if a host trust limitation mechanism is enabled, then apply the > > > iommu_platform=on option so it will go through normal DMA mechanisms. > > > Those will presumably have some way of marking memory as shared with the > > > hypervisor or hardware so that DMA will work. > > > > > > Signed-off-by: David Gibson <david@gibson.dropbear.id.au> > > > > Good, it's just too easy to forget them at the moment and get hopelessly > > confused. > > > > > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > > > > --- > > > hw/core/machine.c | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > > index b599b0ba65..2a723bf07b 100644 > > > --- a/hw/core/machine.c > > > +++ b/hw/core/machine.c > > > @@ -28,6 +28,8 @@ > > > #include "hw/mem/nvdimm.h" > > > #include "migration/vmstate.h" > > > #include "exec/host-trust-limitation.h" > > > +#include "hw/virtio/virtio.h" > > > +#include "hw/virtio/virtio-pci.h" > > > > > > GlobalProperty hw_compat_5_0[] = { > > > { "virtio-balloon-device", "page-poison", "false" }, > > > @@ -1161,6 +1163,15 @@ void machine_run_board_init(MachineState *machine) > > > * areas. > > > */ > > > machine_set_mem_merge(OBJECT(machine), false, &error_abort); > > > + > > > + /* > > > + * Virtio devices can't count on directly accessing guest > > > + * memory, so they need iommu_platform=on to use normal DMA > > > + * mechanisms. That requires disabling legacy virtio support > > > + * for virtio pci devices > > > + */ > > > + object_register_sugar_prop(TYPE_VIRTIO_PCI, "disable-legacy", "on"); > > What about non-transitional devices (eg. vhost-user-fs-pci) ? They don't know > about "disable-legacy" since they don't need it. > Ok, it looks like we should add a bool argument to object_register_sugar_prop() that sets the .optional field of GlobalProperty. > > > + object_register_sugar_prop(TYPE_VIRTIO_DEVICE, "iommu_platform", "on"); > > > } > > > > > > machine_class->init(machine); > > > -- > > > 2.26.2 > > > > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > > >
next prev parent reply other threads:[~2020-08-13 8:19 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-24 2:57 [for-5.2 v4 00/10] Generalize memory encryption models David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 01/10] host trust limitation: Introduce new host trust limitation interface David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 02/10] host trust limitation: Handle memory encryption via interface David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 03/10] host trust limitation: Move side effect out of machine_set_memory_encryption() David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 04/10] host trust limitation: Rework the "memory-encryption" property David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 05/10] host trust limitation: Decouple kvm_memcrypt_*() helpers from KVM David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 06/10] host trust limitation: Add Error ** to HostTrustLimitation::kvm_init David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 07/10] spapr: Add PEF based host trust limitation David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-24 2:57 ` [for-5.2 v4 08/10] spapr: PEF: block migration David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-27 15:01 ` Dr. David Alan Gilbert 2020-07-27 15:01 ` Dr. David Alan Gilbert 2020-07-24 2:57 ` [for-5.2 v4 09/10] host trust limitation: Alter virtio default properties for protected guests David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-27 15:05 ` Dr. David Alan Gilbert 2020-07-27 15:05 ` Dr. David Alan Gilbert 2020-08-13 7:43 ` Greg Kurz 2020-08-13 7:43 ` Greg Kurz 2020-08-13 8:19 ` Greg Kurz [this message] 2020-08-13 8:19 ` Greg Kurz 2020-09-07 15:10 ` Halil Pasic 2020-09-07 15:10 ` Halil Pasic 2020-09-11 2:04 ` David Gibson 2020-09-11 2:04 ` David Gibson 2020-09-11 13:49 ` Halil Pasic 2020-09-11 13:49 ` Halil Pasic 2020-07-24 2:57 ` [for-5.2 v4 10/10] s390: Recognize host-trust-limitation option David Gibson 2020-07-24 2:57 ` David Gibson 2020-07-27 15:50 ` Cornelia Huck 2020-07-27 15:50 ` Cornelia Huck 2020-08-03 7:40 ` Janosch Frank 2020-08-03 7:40 ` Janosch Frank 2020-08-06 6:14 ` David Gibson 2020-08-06 6:14 ` David Gibson 2020-08-06 7:18 ` David Hildenbrand 2020-08-06 7:18 ` David Hildenbrand 2020-08-03 7:49 ` Janosch Frank 2020-08-03 7:49 ` Janosch Frank 2020-08-03 7:54 ` David Gibson 2020-08-03 7:54 ` David Gibson 2020-08-03 8:07 ` Janosch Frank 2020-08-03 8:07 ` Janosch Frank 2020-08-03 8:14 ` David Gibson 2020-08-03 8:14 ` David Gibson 2020-08-03 8:33 ` Cornelia Huck 2020-08-03 8:33 ` Cornelia Huck 2020-09-07 15:22 ` Halil Pasic 2020-09-07 15:22 ` Halil Pasic 2020-09-10 11:36 ` Cornelia Huck 2020-09-10 11:36 ` Cornelia Huck 2020-09-10 18:29 ` Halil Pasic 2020-09-10 18:29 ` Halil Pasic 2020-09-11 0:07 ` David Gibson 2020-09-11 0:07 ` David Gibson 2020-09-11 6:25 ` Greg Kurz 2020-09-11 6:25 ` Greg Kurz 2020-09-11 12:45 ` Halil Pasic 2020-09-11 12:45 ` Halil Pasic
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