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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: brijesh.singh@amd.com, pair@us.ibm.com, pasic@linux.ibm.com,
	qemu-devel@nongnu.org, cohuck@redhat.com,
	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 07/13] confidential guest support: Introduce cgs "ready" flag
Date: Mon, 18 Jan 2021 19:47:30 +0000	[thread overview]
Message-ID: <20210118194730.GH9899@work-vm> (raw)
In-Reply-To: <20210113235811.1909610-8-david@gibson.dropbear.id.au>

* David Gibson (david@gibson.dropbear.id.au) wrote:
> The platform specific details of mechanisms for implementing
> confidential guest support may require setup at various points during
> initialization.  Thus, it's not really feasible to have a single cgs
> initialization hook, but instead each mechanism needs its own
> initialization calls in arch or machine specific code.
> 
> However, to make it harder to have a bug where a mechanism isn't
> properly initialized under some circumstances, we want to have a
> common place, relatively late in boot, where we verify that cgs has
> been initialized if it was requested.
> 
> This patch introduces a ready flag to the ConfidentialGuestSupport
> base type to accomplish this, which we verify just before the machine
> specific initialization function.

You may find you need to define 'ready' and the answer might be a bit
variable; for example, on SEV there's a setup bit and then you may end
up doing an attestation and receiving some data before you actaully let
the guest execute code.   Is it ready before it's received the
attestation response or only when it can run code?
Is a Power or 390 machine 'ready' before it's executed the magic
instruction to enter the confidential mode?

Dave

> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  hw/core/machine.c                         | 8 ++++++++
>  include/exec/confidential-guest-support.h | 2 ++
>  target/i386/sev.c                         | 2 ++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 94194ab82d..5a7433332b 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -1190,6 +1190,14 @@ void machine_run_board_init(MachineState *machine)
>      }
>  
>      if (machine->cgs) {
> +        /*
> +         * Where confidential guest support is initialized depends on
> +         * the specific mechanism in use.  But, we need to make sure
> +         * it's ready by now.  If it isn't, that's a bug in the
> +         * implementation of that cgs mechanism.
> +         */
> +        assert(machine->cgs->ready);
> +
>          /*
>           * With confidential guests, the host can't see the real
>           * contents of RAM, so there's no point in it trying to merge
> diff --git a/include/exec/confidential-guest-support.h b/include/exec/confidential-guest-support.h
> index 5f131023ba..bcaf6c9f49 100644
> --- a/include/exec/confidential-guest-support.h
> +++ b/include/exec/confidential-guest-support.h
> @@ -27,6 +27,8 @@ OBJECT_DECLARE_SIMPLE_TYPE(ConfidentialGuestSupport, CONFIDENTIAL_GUEST_SUPPORT)
>  
>  struct ConfidentialGuestSupport {
>      Object parent;
> +
> +    bool ready;
>  };
>  
>  typedef struct ConfidentialGuestSupportClass {
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index e2b41ef342..3d94635397 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -737,6 +737,8 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
>      qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
>      qemu_add_vm_change_state_handler(sev_vm_state_change, sev);
>  
> +    cgs->ready = true;
> +
>      return 0;
>  err:
>      sev_guest = NULL;
> -- 
> 2.29.2
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK


  parent reply	other threads:[~2021-01-18 19:49 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
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 [this message]
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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