On 4/22/24 15:11, Martin Kletzander wrote:
On Mon, Apr 22, 2024 at 02:02:28PM +0100, Daniel P. Berrangé wrote:
On Mon, Apr 22, 2024 at 02:29:32PM +0200, Martin Kletzander wrote:
On Mon, Apr 22, 2024 at 01:38:38PM +0200, Michal Privoznik wrote:
This is a helper that parses /sys/devices/system/cpu/isolated into a virBitmap. It's going to be needed soon.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/libvirt_private.syms | 1 + src/util/virhostcpu.c | 21 +++++++++++++++++++++ src/util/virhostcpu.h | 1 + 3 files changed, 23 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 839fe4f545..ed85f022e4 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -2502,6 +2502,7 @@ virHostCPUGetCount; virHostCPUGetCPUID; virHostCPUGetHaltPollTime; virHostCPUGetInfo; +virHostCPUGetIsolated; virHostCPUGetKVMMaxVCPUs; virHostCPUGetMap; virHostCPUGetMicrocodeVersion; diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c index 01de69c0d1..e61eb12414 100644 --- a/src/util/virhostcpu.c +++ b/src/util/virhostcpu.c @@ -1151,6 +1151,27 @@ virHostCPUGetAvailableCPUsBitmap(void) return g_steal_pointer(&bitmap); }
+/** + * virHostCPUGetIsolated: + * + * Returns a bitmap of isolated CPUs (e.g. those passed to isolcpus= kernel + * cmdline). + */ +virBitmap * +virHostCPUGetIsolated(void) +{
So this function will fail on anything non-Linux and we probably do not want that. If the platform does not support isolcpus, then it is fine to return an empty bitmap.
+#ifdef __linux__ + virBitmap *ret = NULL; + + virFileReadValueBitmap(&ret, "%s/cpu/isolated", SYSFS_SYSTEM_PATH); +
And this will fail (return NULL) on any system without isolcpus=, which is also probably something we do not want.
The 'isolated' file exists, but is empty on such systems. So IIUC you're saying virFileReadValueBitmap will fail to parse the empty string and report it as an error ?
Yes, virBitmapParseUnlimited() will call virBitmapParseInternal() which checks:
[...] const char *cur = str; [...] if (!str) goto error;
virSkipSpaces(&cur);
if (*cur == '\0') goto error;
and to make sure I tested it and the virBitmap * is NULL and the function returns -1.
Oh, I didn't realize an empty file (well, "\n\0") makes this function fail. That complicates things a bit. Let me see what can be done about it. Michal