[libvirt PATCH v2 09/12] qemu: report max number of SEV guests
Daniel P. Berrangé
berrange at redhat.com
Fri Dec 10 11:37:32 UTC 2021
Different CPU generations have different limits on the number
of SEV/SEV-ES guests that can be run. Since both limits come
from the same overall set, there is typically also BIOS config
to set the tradeoff betweeen SEV and SEV-ES guest limits.
This is important information to expose for a mgmt application
scheduling guests to hosts.
Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
---
src/qemu/qemu_capabilities.c | 38 +++++++++++++++++++
src/qemu/qemu_driver.c | 10 +++++
.../domaincapsdata/qemu_2.12.0-q35.x86_64.xml | 2 +-
.../domaincapsdata/qemu_2.12.0-tcg.x86_64.xml | 2 +-
tests/domaincapsdata/qemu_2.12.0.x86_64.xml | 2 +-
.../domaincapsdata/qemu_6.0.0-q35.x86_64.xml | 2 +-
.../domaincapsdata/qemu_6.0.0-tcg.x86_64.xml | 2 +-
tests/domaincapsdata/qemu_6.0.0.x86_64.xml | 2 +-
8 files changed, 54 insertions(+), 6 deletions(-)
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 4ffd0a98a2..456ce1b72e 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -1897,6 +1897,8 @@ virQEMUCapsSEVInfoCopy(virSEVCapability **dst,
tmp->cbitpos = src->cbitpos;
tmp->reduced_phys_bits = src->reduced_phys_bits;
+ tmp->max_guests = src->max_guests;
+ tmp->max_es_guests = src->max_es_guests;
*dst = g_steal_pointer(&tmp);
return 0;
@@ -3286,6 +3288,30 @@ virQEMUCapsProbeQMPGICCapabilities(virQEMUCaps *qemuCaps,
}
+static void
+virQEMUCapsGetSEVMaxGuests(virSEVCapability *caps)
+{
+# if __x86_64__
+ uint32_t eax, ebx, ecx, edx;
+ asm("xor %%ebx, %%ebx;" /* clear the other registers as some cpuid */
+ "xor %%edx, %%edx;" /* functions may use them as additional arguments */
+ "cpuid;"
+ : "=a" (eax),
+ "=b" (ebx),
+ "=c" (ecx),
+ "=d" (edx)
+ : "0" (0x8000001F),
+ "c" (0)
+ : "cc");
+
+ caps->max_guests = ecx - edx + 1;
+ caps->max_es_guests = edx - 1;
+# else
+ VIR_WARN("Unexpectedly asked for SEV guest count on non-x86_64 arch");
+ caps->max_guests = caps->max_es_guests = 0;
+# endif
+}
+
static int
virQEMUCapsProbeQMPSEVCapabilities(virQEMUCaps *qemuCaps,
qemuMonitor *mon)
@@ -3305,6 +3331,8 @@ virQEMUCapsProbeQMPSEVCapabilities(virQEMUCaps *qemuCaps,
return 0;
}
+ virQEMUCapsGetSEVMaxGuests(caps);
+
virSEVCapabilitiesFree(qemuCaps->sevCapabilities);
qemuCaps->sevCapabilities = caps;
return 0;
@@ -4084,6 +4112,14 @@ virQEMUCapsParseSEVInfo(virQEMUCaps *qemuCaps, xmlXPathContextPtr ctxt)
return -1;
}
+
+ /* We probe this every time because the values
+ * can change on every reboot via firmware
+ * config tunables. It is cheap to query so
+ * lack of caching is a non-issue
+ */
+ virQEMUCapsGetSEVMaxGuests(sev);
+
qemuCaps->sevCapabilities = g_steal_pointer(&sev);
return 0;
}
@@ -6344,6 +6380,8 @@ virQEMUCapsFillDomainFeatureSEVCaps(virQEMUCaps *qemuCaps,
domCaps->sev->cert_chain = g_strdup(cap->cert_chain);
domCaps->sev->cbitpos = cap->cbitpos;
domCaps->sev->reduced_phys_bits = cap->reduced_phys_bits;
+ domCaps->sev->max_guests = cap->max_guests;
+ domCaps->sev->max_es_guests = cap->max_es_guests;
}
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 1bf1938634..572e09be9f 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -19934,6 +19934,16 @@ qemuGetSEVInfoToParams(virQEMUCaps *qemuCaps,
sev->reduced_phys_bits) < 0)
goto cleanup;
+ if (virTypedParamsAddUInt(&sevParams, &n, &maxpar,
+ VIR_NODE_SEV_MAX_GUESTS,
+ sev->max_guests) < 0)
+ goto cleanup;
+
+ if (virTypedParamsAddUInt(&sevParams, &n, &maxpar,
+ VIR_NODE_SEV_MAX_ES_GUESTS,
+ sev->max_es_guests) < 0)
+ goto cleanup;
+
*params = g_steal_pointer(&sevParams);
*nparams = n;
return 0;
diff --git a/tests/domaincapsdata/qemu_2.12.0-q35.x86_64.xml b/tests/domaincapsdata/qemu_2.12.0-q35.x86_64.xml
index 26816ff066..6956f9af07 100644
--- a/tests/domaincapsdata/qemu_2.12.0-q35.x86_64.xml
+++ b/tests/domaincapsdata/qemu_2.12.0-q35.x86_64.xml
@@ -205,7 +205,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
diff --git a/tests/domaincapsdata/qemu_2.12.0-tcg.x86_64.xml b/tests/domaincapsdata/qemu_2.12.0-tcg.x86_64.xml
index 5840a8b921..c6408d154c 100644
--- a/tests/domaincapsdata/qemu_2.12.0-tcg.x86_64.xml
+++ b/tests/domaincapsdata/qemu_2.12.0-tcg.x86_64.xml
@@ -215,7 +215,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
diff --git a/tests/domaincapsdata/qemu_2.12.0.x86_64.xml b/tests/domaincapsdata/qemu_2.12.0.x86_64.xml
index 21d1b6946e..918439e4a0 100644
--- a/tests/domaincapsdata/qemu_2.12.0.x86_64.xml
+++ b/tests/domaincapsdata/qemu_2.12.0.x86_64.xml
@@ -205,7 +205,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
diff --git a/tests/domaincapsdata/qemu_6.0.0-q35.x86_64.xml b/tests/domaincapsdata/qemu_6.0.0-q35.x86_64.xml
index 3415d44019..8733b79a31 100644
--- a/tests/domaincapsdata/qemu_6.0.0-q35.x86_64.xml
+++ b/tests/domaincapsdata/qemu_6.0.0-q35.x86_64.xml
@@ -227,7 +227,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
diff --git a/tests/domaincapsdata/qemu_6.0.0-tcg.x86_64.xml b/tests/domaincapsdata/qemu_6.0.0-tcg.x86_64.xml
index f58be3af6c..0382bdaf5a 100644
--- a/tests/domaincapsdata/qemu_6.0.0-tcg.x86_64.xml
+++ b/tests/domaincapsdata/qemu_6.0.0-tcg.x86_64.xml
@@ -233,7 +233,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
diff --git a/tests/domaincapsdata/qemu_6.0.0.x86_64.xml b/tests/domaincapsdata/qemu_6.0.0.x86_64.xml
index 0a2615c519..30ea787a75 100644
--- a/tests/domaincapsdata/qemu_6.0.0.x86_64.xml
+++ b/tests/domaincapsdata/qemu_6.0.0.x86_64.xml
@@ -227,7 +227,7 @@
<sev supported='yes'>
<cbitpos>47</cbitpos>
<reducedPhysBits>1</reducedPhysBits>
- <maxGuests>0</maxGuests>
+ <maxGuests>15</maxGuests>
<maxESGuests>0</maxESGuests>
</sev>
</features>
--
2.33.1
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