[libvirt] [PATCH v3 1/9] qemu: provide support to query the SEV capability

John Ferlan jferlan at redhat.com
Fri Mar 23 19:18:59 UTC 2018



On 03/14/2018 11:44 AM, Brijesh Singh wrote:
> QEMU version >= 2.12 provides support for launching an encrypted VMs on
> AMD x86 platform using Secure Encrypted Virtualization (SEV) feature.
> This patch adds support to query the SEV capability from the qemu.
> 
> Reviewed-by: "Daniel P. Berrangé" <berrange at redhat.com>
> Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
> ---
>  src/conf/domain_capabilities.h | 13 ++++++++
>  src/qemu/qemu_capabilities.c   | 38 ++++++++++++++++++++++
>  src/qemu/qemu_capabilities.h   |  1 +
>  src/qemu/qemu_capspriv.h       |  4 +++
>  src/qemu/qemu_monitor.c        |  9 ++++++
>  src/qemu/qemu_monitor.h        |  3 ++
>  src/qemu/qemu_monitor_json.c   | 73 ++++++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_monitor_json.h   |  3 ++
>  8 files changed, 144 insertions(+)
> 

Now that the 2.12 capabilities were added, I started looking through
each of the upstream patch series that would make use of it - this is
just "next" on my list.

I tried applying just this patch, but kept getting:

29) caps_2.12.0(x86_64)
... libvirt: QEMU Driver error : internal error: query-cpu-definitions
reply data was not an array

a small bit of debugging found that qemuMonitorJSONGetCPUDefinitions was
returning NULL for @data after/when the "query-sev-capabilities".

I narrowed it down into the virQEMUCapsInitQMPMonitor when run during
qemucapabilitiestest (see [1])

> diff --git a/src/conf/domain_capabilities.h b/src/conf/domain_capabilities.h
> index fa4c1e442f57..72e9daf9120f 100644
> --- a/src/conf/domain_capabilities.h
> +++ b/src/conf/domain_capabilities.h
> @@ -137,6 +137,19 @@ struct _virDomainCapsCPU {
>      virDomainCapsCPUModelsPtr custom;
>  };
>  
> +/*
> + * SEV capabilities
> + */
> +typedef struct _virSEVCapability virSEVCapability;
> +typedef virSEVCapability *virSEVCapabilityPtr;
> +struct _virSEVCapability {
> +    char *pdh;
> +    char *cert_chain;
> +    unsigned int cbitpos;
> +    unsigned int reduced_phys_bits;
> +};
> +
> +
>  struct _virDomainCaps {
>      virObjectLockable parent;
>  
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 3eb5ed6d1a60..6da7cf7477c7 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -459,6 +459,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
>                "pl011",
>                "machine.pseries.max-cpu-compat",
>                "dump-completed",
> +              "sev",

This should also be "sev-guest" to be consistent with other
virQEMUCapsObjectTypes entries naming.

BTW: You can/should pull out this entry, the one in
virQEMUCapsObjectTypes and the qemu_capabilities.h change to add the
entry to virQEMUCapsFlags, then build and run:

  VIR_TEST_REGENERATE_OUTPUT=1 tests/qemucapabilitiestest

in order to get/see the changed
tests/qemucapabilitiesdata/caps_2.12.0.x86_64.xml file.


>      );
>  
>  
> @@ -525,6 +526,8 @@ struct _virQEMUCaps {
>      size_t ngicCapabilities;
>      virGICCapability *gicCapabilities;
>  
> +    virSEVCapability *sevCapabilities;
> +
>      virQEMUCapsHostCPUData kvmCPU;
>      virQEMUCapsHostCPUData tcgCPU;
>  };
> @@ -1694,6 +1697,7 @@ struct virQEMUCapsStringFlags virQEMUCapsObjectTypes[] = {
>      { "sclplmconsole", QEMU_CAPS_DEVICE_SCLPLMCONSOLE },
>      { "isa-serial", QEMU_CAPS_DEVICE_ISA_SERIAL },
>      { "pl011", QEMU_CAPS_DEVICE_PL011 },
> +    { "sev-guest", QEMU_CAPS_SEV },
>  };
>  
>  static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsVirtioBalloon[] = {
> @@ -2770,6 +2774,21 @@ virQEMUCapsSetGICCapabilities(virQEMUCapsPtr qemuCaps,
>      qemuCaps->ngicCapabilities = ncapabilities;
>  }
>  
> +void
> +virQEMUCapsSetSEVCapabilities(virQEMUCapsPtr qemuCaps,
> +                              virSEVCapability *capabilities)
> +{
> +    virSEVCapability *cap = qemuCaps->sevCapabilities;
> +
> +    if (cap) {
> +        VIR_FREE(cap->pdh);
> +        VIR_FREE(cap->cert_chain);
> +    }
> +
> +    VIR_FREE(qemuCaps->sevCapabilities);
> +
> +    qemuCaps->sevCapabilities = capabilities;
> +}
>  
>  static int
>  virQEMUCapsProbeQMPCommands(virQEMUCapsPtr qemuCaps,
> @@ -3273,6 +3292,19 @@ virQEMUCapsProbeQMPGICCapabilities(virQEMUCapsPtr qemuCaps,
>      return 0;
>  }
>  
> +static int
> +virQEMUCapsProbeQMPSEVCapabilities(virQEMUCapsPtr qemuCaps,
> +                                   qemuMonitorPtr mon)
> +{
> +    virSEVCapability *caps = NULL;
> +
> +    if (qemuMonitorGetSEVCapabilities(mon, &caps) < 0)
> +        return -1;
> +
> +    virQEMUCapsSetSEVCapabilities(qemuCaps, caps);
> +
> +    return 0;
> +}
>  
>  bool
>  virQEMUCapsCPUFilterFeatures(const char *name,
> @@ -4906,6 +4938,12 @@ virQEMUCapsInitQMPMonitor(virQEMUCapsPtr qemuCaps,
>          virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION))
>          virQEMUCapsSet(qemuCaps, QEMU_CAPS_CPU_CACHE);
>  
> +    /* Probe for SEV capabilities */
> +    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SEV)) {
> +        if (virQEMUCapsProbeQMPSEVCapabilities(qemuCaps, mon) < 0)
> +            virQEMUCapsClear(qemuCaps, QEMU_CAPS_SEV);

[1]
If I change the Clear to be a goto cleanup, then a slightly different
error appears:

libvirt: QEMU Driver error : internal error: 'cbitpos' field is missing

Checking the output of a

  LIBVIRT_DEBUG=1 VIR_TEST_DEBUG=1 VIR_TEST_RANGE=29 make -C tests check
TESTS=qemucapabilitiestest

gives a bit of a hint in the test-suite.log output:

2018-03-23 19:08:52.819+0000: 11727: debug :
qemuMonitorTestAddResponse:108 : Adding response to monitor command: '{
 "return": {   },   "id": "libvirt-1" }
...

So that says to me that we perhaps need some mocked output. Although I'm
not 100% sure - it doesn't seem previous adjustments needed those, but
there's lots that changes in this capabilities space and I'm not always
up to date on the mocking code.

BTW: resetting the last error in this case didn't fix the problem - it
just moved the cheese back to the original error. So there's some mocked
buffer somewhere that's being read - I'm hoping someone with a fresher
memory on how this works will be able to debug faster than I.

> +    }
> +
>      ret = 0;
>   cleanup:
>      return ret;
> diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
> index c2ec2be19311..02acae491ab5 100644
> --- a/src/qemu/qemu_capabilities.h
> +++ b/src/qemu/qemu_capabilities.h
> @@ -444,6 +444,7 @@ typedef enum {
>      QEMU_CAPS_DEVICE_PL011, /* -device pl011 (not user-instantiable) */
>      QEMU_CAPS_MACHINE_PSERIES_MAX_CPU_COMPAT, /* -machine pseries,max-cpu-compat= */
>      QEMU_CAPS_DUMP_COMPLETED, /* DUMP_COMPLETED event */
> +    QEMU_CAPS_SEV, /* -object sev-guest,... */

I think this should be QEMU_CAPS_SEV_GUEST  (it's a consistency in
naming thing)

I'll defer to Dan and Peter on the rest...

John

>  
>      QEMU_CAPS_LAST /* this must always be the last item */
>  } virQEMUCapsFlags;
> diff --git a/src/qemu/qemu_capspriv.h b/src/qemu/qemu_capspriv.h
> index 222f3368e3b6..1fa85cc14f07 100644
> --- a/src/qemu/qemu_capspriv.h
> +++ b/src/qemu/qemu_capspriv.h
> @@ -86,6 +86,10 @@ virQEMUCapsSetGICCapabilities(virQEMUCapsPtr qemuCaps,
>                                virGICCapability *capabilities,
>                                size_t ncapabilities);
>  
> +void
> +virQEMUCapsSetSEVCapabilities(virQEMUCapsPtr qemuCaps,
> +                              virSEVCapability *capabilities);
> +
>  int
>  virQEMUCapsParseHelpStr(const char *qemu,
>                          const char *str,
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index 1d67a97789e7..2820714b5c55 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -4007,6 +4007,15 @@ qemuMonitorGetGICCapabilities(qemuMonitorPtr mon,
>      return qemuMonitorJSONGetGICCapabilities(mon, capabilities);
>  }
>  
> +int
> +qemuMonitorGetSEVCapabilities(qemuMonitorPtr mon,
> +                              virSEVCapability **capabilities)
> +{
> +    QEMU_CHECK_MONITOR_JSON(mon);
> +
> +    return qemuMonitorJSONGetSEVCapabilities(mon, capabilities);
> +}
> +
>  
>  int
>  qemuMonitorNBDServerStart(qemuMonitorPtr mon,
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index adfa87aba91b..aaa14f66fdfb 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -767,6 +767,9 @@ int qemuMonitorSetMigrationCapability(qemuMonitorPtr mon,
>  int qemuMonitorGetGICCapabilities(qemuMonitorPtr mon,
>                                    virGICCapability **capabilities);
>  
> +int qemuMonitorGetSEVCapabilities(qemuMonitorPtr mon,
> +                                  virSEVCapability **capabilities);
> +
>  typedef enum {
>    QEMU_MONITOR_MIGRATE_BACKGROUND       = 1 << 0,
>    QEMU_MONITOR_MIGRATE_NON_SHARED_DISK  = 1 << 1, /* migration with non-shared storage with full disk copy */
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index 08dfffdf6435..c51b98d2bda7 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -6398,6 +6398,79 @@ qemuMonitorJSONGetGICCapabilities(qemuMonitorPtr mon,
>      return ret;
>  }
>  
> +int
> +qemuMonitorJSONGetSEVCapabilities(qemuMonitorPtr mon,
> +                                  virSEVCapability **capabilities)
> +{
> +    int ret = -1;
> +    virJSONValuePtr cmd;
> +    virJSONValuePtr reply = NULL;
> +    virJSONValuePtr caps;
> +    virSEVCapability *capability = NULL;
> +    const char *pdh = NULL, *cert_chain = NULL;
> +    int cbitpos, reduced_phys_bits;
> +
> +    *capabilities = NULL;
> +
> +    if (!(cmd = qemuMonitorJSONMakeCommand("query-sev-capabilities",
> +                                           NULL)))
> +        return -1;
> +
> +    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
> +        goto cleanup;
> +
> +
> +    if (qemuMonitorJSONCheckError(cmd, reply) < 0)
> +        goto cleanup;
> +
> +    caps = virJSONValueObjectGetObject(reply, "return");
> +
> +    if (virJSONValueObjectGetNumberInt(caps, "cbitpos", &cbitpos) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("'cbitpos' field is missing"));
> +        goto cleanup;
> +    }
> +
> +    if (virJSONValueObjectGetNumberInt(caps, "reduced-phys-bits",
> +                                       &reduced_phys_bits) < 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("'reduced-phys-bits' field is missing"));
> +        goto cleanup;
> +    }
> +
> +    if (!(pdh = virJSONValueObjectGetString(caps, "pdh"))) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("'pdh' field is missing"));
> +        goto cleanup;
> +    }
> +
> +    if (!(cert_chain = virJSONValueObjectGetString(caps, "cert-chain"))) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                       _("'cert-chain' field is missing"));
> +        goto cleanup;
> +    }
> +
> +    if (VIR_ALLOC(capability) < 0)
> +        goto cleanup;
> +
> +    if (VIR_STRDUP(capability->pdh, pdh) < 0)
> +        goto cleanup;
> +
> +    if (VIR_STRDUP(capability->cert_chain, cert_chain) < 0)
> +        goto cleanup;
> +
> +    capability->cbitpos = cbitpos;
> +    capability->reduced_phys_bits = reduced_phys_bits;
> +    *capabilities = capability;
> +    ret = 0;
> +
> + cleanup:
> +    virJSONValueFree(cmd);
> +    virJSONValueFree(reply);
> +
> +    return ret;
> +}
> +
>  static virJSONValuePtr
>  qemuMonitorJSONBuildInetSocketAddress(const char *host,
>                                        const char *port)
> diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
> index ec243becc4ae..305f789902e9 100644
> --- a/src/qemu/qemu_monitor_json.h
> +++ b/src/qemu/qemu_monitor_json.h
> @@ -152,6 +152,9 @@ int qemuMonitorJSONSetMigrationCapability(qemuMonitorPtr mon,
>  int qemuMonitorJSONGetGICCapabilities(qemuMonitorPtr mon,
>                                        virGICCapability **capabilities);
>  
> +int qemuMonitorJSONGetSEVCapabilities(qemuMonitorPtr mon,
> +                                      virSEVCapability **capabilities);
> +
>  int qemuMonitorJSONMigrate(qemuMonitorPtr mon,
>                             unsigned int flags,
>                             const char *uri);
> 




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