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

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Hi John,


On 03/23/2018 02:18 PM, John Ferlan wrote:


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@xxxxxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
  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])

I have not tried latest libvirt yet, I will try this today and debug to see what we are missing. I did the 'make check' before submitting the patch but at that time QEMU 2.12 was not available and we did not had updated caps_2.12.0.x86_64.xml and caps_2.12.0.x86_64.replies.

I will investigate a bit more and update with my findings.

thanks


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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