From f91f9f254ba10e94468663b23d0b780c240df268 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 5 May 2020 17:00:30 +1000 Subject: confidential guest support: Introduce new confidential guest support class Several architectures have mechanisms which are designed to protect guest memory from interference or eavesdropping by a compromised hypervisor. AMD SEV does this with in-chip memory encryption and Intel's TDX can do similar things. POWER's Protected Execution Framework (PEF) accomplishes a similar goal using an ultravisor and new memory protection features, instead of encryption. To (partially) unify handling for these, this introduces a new ConfidentialGuestSupport QOM base class. "Confidential" is kind of vague, but "confidential computing" seems to be the buzzword about these schemes, and "secure" or "protected" are often used in connection to unrelated things (such as hypervisor-from-guest or guest-from-guest security). The "support" in the name is significant because in at least some of the cases it requires the guest to take specific actions in order to protect itself from hypervisor eavesdropping. Signed-off-by: David Gibson --- include/exec/confidential-guest-support.h | 38 +++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 include/exec/confidential-guest-support.h (limited to 'include/exec') diff --git a/include/exec/confidential-guest-support.h b/include/exec/confidential-guest-support.h new file mode 100644 index 0000000000..3db6380e63 --- /dev/null +++ b/include/exec/confidential-guest-support.h @@ -0,0 +1,38 @@ +/* + * QEMU Confidential Guest support + * This interface describes the common pieces between various + * schemes for protecting guest memory or other state against a + * compromised hypervisor. This includes memory encryption (AMD's + * SEV and Intel's MKTME) or special protection modes (PEF on POWER, + * or PV on s390x). + * + * Copyright Red Hat. + * + * Authors: + * David Gibson + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + * + */ +#ifndef QEMU_CONFIDENTIAL_GUEST_SUPPORT_H +#define QEMU_CONFIDENTIAL_GUEST_SUPPORT_H + +#ifndef CONFIG_USER_ONLY + +#include "qom/object.h" + +#define TYPE_CONFIDENTIAL_GUEST_SUPPORT "confidential-guest-support" +OBJECT_DECLARE_SIMPLE_TYPE(ConfidentialGuestSupport, CONFIDENTIAL_GUEST_SUPPORT) + +struct ConfidentialGuestSupport { + Object parent; +}; + +typedef struct ConfidentialGuestSupportClass { + ObjectClass parent; +} ConfidentialGuestSupportClass; + +#endif /* !CONFIG_USER_ONLY */ + +#endif /* QEMU_CONFIDENTIAL_GUEST_SUPPORT_H */ -- cgit v1.2.3-55-g7522 From abc27d4241f99bfaebb0b843b9a967d557ac10e8 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 20 Oct 2020 17:01:19 +1100 Subject: confidential guest support: Introduce cgs "ready" flag 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, 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 in qemu_machine_creation_done(). Signed-off-by: David Gibson Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Greg Kurz --- include/exec/confidential-guest-support.h | 24 ++++++++++++++++++++++++ softmmu/vl.c | 10 ++++++++++ target/i386/sev.c | 2 ++ 3 files changed, 36 insertions(+) (limited to 'include/exec') diff --git a/include/exec/confidential-guest-support.h b/include/exec/confidential-guest-support.h index 3db6380e63..ba2dd4b5df 100644 --- a/include/exec/confidential-guest-support.h +++ b/include/exec/confidential-guest-support.h @@ -27,6 +27,30 @@ OBJECT_DECLARE_SIMPLE_TYPE(ConfidentialGuestSupport, CONFIDENTIAL_GUEST_SUPPORT) struct ConfidentialGuestSupport { Object parent; + + /* + * ready: flag set by CGS initialization code once it's ready to + * start executing instructions in a potentially-secure + * guest + * + * The definition here is a bit fuzzy, because this is essentially + * part of a self-sanity-check, rather than a strict mechanism. + * + * It's not feasible to have a single point in the common machine + * init path to configure confidential guest support, because + * different mechanisms have different interdependencies requiring + * initialization in different places, often in arch or machine + * type specific code. It's also usually not possible to check + * for invalid configurations until that initialization code. + * That means it would be very easy to have a bug allowing CGS + * init to be bypassed entirely in certain configurations. + * + * Silently ignoring a requested security feature would be bad, so + * to avoid that we check late in init that this 'ready' flag is + * set if CGS was requested. If the CGS init hasn't happened, and + * so 'ready' is not set, we'll abort. + */ + bool ready; }; typedef struct ConfidentialGuestSupportClass { diff --git a/softmmu/vl.c b/softmmu/vl.c index 0d934844ff..9eb9dab1fc 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -101,6 +101,7 @@ #include "qemu/plugin.h" #include "qemu/queue.h" #include "sysemu/arch_init.h" +#include "exec/confidential-guest-support.h" #include "ui/qemu-spice.h" #include "qapi/string-input-visitor.h" @@ -2498,6 +2499,8 @@ static void qemu_create_cli_devices(void) static void qemu_machine_creation_done(void) { + MachineState *machine = MACHINE(qdev_get_machine()); + /* Did we create any drives that we failed to create a device for? */ drive_check_orphaned(); @@ -2517,6 +2520,13 @@ static void qemu_machine_creation_done(void) qdev_machine_creation_done(); + if (machine->cgs) { + /* + * Verify that Confidential Guest Support has actually been initialized + */ + assert(machine->cgs->ready); + } + if (foreach_device_config(DEV_GDB, gdbserver_start) < 0) { exit(1); } diff --git a/target/i386/sev.c b/target/i386/sev.c index 590cb31fa8..f9e9b5d8ae 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; -- cgit v1.2.3-55-g7522