[libvirt] [PATCH] qemu: Don't cache microcode version

Jiri Denemark posted 1 patch 6 days ago
Test syntax-check passed
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/libvirt tags/patchew/d25e9e351ed67d045f0c082f0ce6a291ebfd2225.1555324612.git.jdenemar@redhat.com
src/qemu/qemu_capabilities.c | 12 ++++++++----
src/qemu/qemu_capabilities.h |  3 +--
src/qemu/qemu_driver.c       |  9 +--------
tests/testutilsqemu.c        |  2 +-
4 files changed, 11 insertions(+), 15 deletions(-)

[libvirt] [PATCH] qemu: Don't cache microcode version

Posted by Jiri Denemark 6 days ago
My earlier commit be46f61326 was incomplete. It removed caching of
microcode version in the CPU driver, which means the capabilities XML
will see the correct microcode version. But it is also cached in the
QEMU capabilities cache where it is used to detect whether we need to
reprobe QEMU. By missing the second place, the original commit
be46f61326 made the situation even worse since libvirt would report
correct microcode version while still using the old host CPU model
(visible in domain capabilities XML).

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_capabilities.c | 12 ++++++++----
 src/qemu/qemu_capabilities.h |  3 +--
 src/qemu/qemu_driver.c       |  9 +--------
 tests/testutilsqemu.c        |  2 +-
 4 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index da90cd666e..a74dc84056 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -4542,7 +4542,7 @@ virQEMUCapsNewData(const char *binary,
                                            priv->libDir,
                                            priv->runUid,
                                            priv->runGid,
-                                           priv->microcodeVersion,
+                                           virHostCPUGetMicrocodeVersion(),
                                            priv->kernelVersion);
 }
 
@@ -4625,8 +4625,7 @@ virFileCachePtr
 virQEMUCapsCacheNew(const char *libDir,
                     const char *cacheDir,
                     uid_t runUid,
-                    gid_t runGid,
-                    unsigned int microcodeVersion)
+                    gid_t runGid)
 {
     char *capsCacheDir = NULL;
     virFileCachePtr cache = NULL;
@@ -4650,7 +4649,6 @@ virQEMUCapsCacheNew(const char *libDir,
 
     priv->runUid = runUid;
     priv->runGid = runGid;
-    priv->microcodeVersion = microcodeVersion;
     priv->kvmUsable = VIR_TRISTATE_BOOL_ABSENT;
 
     if (uname(&uts) == 0 &&
@@ -4672,8 +4670,11 @@ virQEMUCapsPtr
 virQEMUCapsCacheLookup(virFileCachePtr cache,
                        const char *binary)
 {
+    virQEMUCapsCachePrivPtr priv = virFileCacheGetPriv(cache);
     virQEMUCapsPtr ret = NULL;
 
+    priv->microcodeVersion = virHostCPUGetMicrocodeVersion();
+
     ret = virFileCacheLookup(cache, binary);
 
     VIR_DEBUG("Returning caps %p for %s", ret, binary);
@@ -4727,6 +4728,7 @@ virQEMUCapsPtr
 virQEMUCapsCacheLookupByArch(virFileCachePtr cache,
                              virArch arch)
 {
+    virQEMUCapsCachePrivPtr priv = virFileCacheGetPriv(cache);
     virQEMUCapsPtr ret = NULL;
     const char *binaryFilters[] = {
         "qemu-system-",
@@ -4739,6 +4741,8 @@ virQEMUCapsCacheLookupByArch(virFileCachePtr cache,
     size_t i;
     size_t j;
 
+    priv->microcodeVersion = virHostCPUGetMicrocodeVersion();
+
     for (i = 0; i < ARRAY_CARDINALITY(binaryFilters); i++) {
         for (j = 0; j < ARRAY_CARDINALITY(archs); j++) {
             struct virQEMUCapsSearchData data = {
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index fd7bec7589..8f5656a89b 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -590,8 +590,7 @@ void virQEMUCapsFilterByMachineType(virQEMUCapsPtr qemuCaps,
 virFileCachePtr virQEMUCapsCacheNew(const char *libDir,
                                     const char *cacheDir,
                                     uid_t uid,
-                                    gid_t gid,
-                                    unsigned int microcodeVersion);
+                                    gid_t gid);
 virQEMUCapsPtr virQEMUCapsCacheLookup(virFileCachePtr cache,
                                       const char *binary);
 virQEMUCapsPtr virQEMUCapsCacheLookupCopy(virFileCachePtr cache,
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 7e334d0d8d..4510b0ce60 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -584,8 +584,6 @@ qemuStateInitialize(bool privileged,
     char *hugepagePath = NULL;
     char *memoryBackingPath = NULL;
     size_t i;
-    virCPUDefPtr hostCPU = NULL;
-    unsigned int microcodeVersion = 0;
 
     if (VIR_ALLOC(qemu_driver) < 0)
         return -1;
@@ -808,15 +806,10 @@ qemuStateInitialize(bool privileged,
         run_gid = cfg->group;
     }
 
-    if ((hostCPU = virCPUProbeHost(virArchFromHost())))
-        microcodeVersion = hostCPU->microcodeVersion;
-    virCPUDefFree(hostCPU);
-
     qemu_driver->qemuCapsCache = virQEMUCapsCacheNew(cfg->libDir,
                                                      cfg->cacheDir,
                                                      run_uid,
-                                                     run_gid,
-                                                     microcodeVersion);
+                                                     run_gid);
     if (!qemu_driver->qemuCapsCache)
         goto error;
 
diff --git a/tests/testutilsqemu.c b/tests/testutilsqemu.c
index 3ee8a0c6c6..763f511bcf 100644
--- a/tests/testutilsqemu.c
+++ b/tests/testutilsqemu.c
@@ -740,7 +740,7 @@ int qemuTestDriverInit(virQEMUDriver *driver)
 
     /* Using /dev/null for libDir and cacheDir automatically produces errors
      * upon attempt to use any of them */
-    driver->qemuCapsCache = virQEMUCapsCacheNew("/dev/null", "/dev/null", 0, 0, 0);
+    driver->qemuCapsCache = virQEMUCapsCacheNew("/dev/null", "/dev/null", 0, 0);
     if (!driver->qemuCapsCache)
         goto error;
 
-- 
2.21.0

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Re: [libvirt] [PATCH] qemu: Don't cache microcode version

Posted by Ján Tomko 6 days ago
On Mon, Apr 15, 2019 at 12:36:52PM +0200, Jiri Denemark wrote:
>My earlier commit be46f61326 was incomplete. It removed caching of
>microcode version in the CPU driver, which means the capabilities XML
>will see the correct microcode version. But it is also cached in the
>QEMU capabilities cache where it is used to detect whether we need to
>reprobe QEMU. By missing the second place, the original commit
>be46f61326 made the situation even worse since libvirt would report
>correct microcode version while still using the old host CPU model
>(visible in domain capabilities XML).
>
>Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
>---
> src/qemu/qemu_capabilities.c | 12 ++++++++----
> src/qemu/qemu_capabilities.h |  3 +--
> src/qemu/qemu_driver.c       |  9 +--------
> tests/testutilsqemu.c        |  2 +-
> 4 files changed, 11 insertions(+), 15 deletions(-)
>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

Jano
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