* [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
@ 2017-06-15 9:58 Juergen Gross
2017-06-20 11:05 ` Wei Liu
2017-06-21 14:24 ` Olaf Hering
0 siblings, 2 replies; 6+ messages in thread
From: Juergen Gross @ 2017-06-15 9:58 UTC (permalink / raw)
To: xen-devel; +Cc: Juergen Gross, wei.liu2, ian.jackson
Instead of relying on cpuid instruction behaviour to tell which domain
type we are just try asking the kernel via the appropriate sysfs node
(added in Linux kernel 4.13).
Keep the old detection logic as a fallback for older kernels.
Signed-off-by: Juergen Gross <jgross@suse.com>
---
tools/misc/xen-detect.c | 129 +++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 121 insertions(+), 8 deletions(-)
diff --git a/tools/misc/xen-detect.c b/tools/misc/xen-detect.c
index 787b5da90d..a62747d316 100644
--- a/tools/misc/xen-detect.c
+++ b/tools/misc/xen-detect.c
@@ -24,6 +24,11 @@
* DEALINGS IN THE SOFTWARE.
*/
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <limits.h>
+#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
@@ -33,6 +38,15 @@
#include <unistd.h>
#include <getopt.h>
+enum guest_type {
+ XEN_PV = 1,
+ XEN_HVM = 2,
+ XEN_NONE = 3
+};
+
+static char *type;
+static char *ver;
+
static void cpuid(uint32_t idx, uint32_t *regs, int pv_context)
{
#ifdef __i386__
@@ -75,6 +89,9 @@ static int check_for_xen(int pv_context)
found:
cpuid(base + 1, regs, pv_context);
+ if ( regs[0] )
+ asprintf(&ver, "V%u.%u",
+ (uint16_t)(regs[0] >> 16), (uint16_t)regs[0]);
return regs[0];
}
@@ -91,14 +108,104 @@ static void usage(void)
printf(" -h, --help Display this information\n");
printf(" -q, --quiet Quiesce normal informational output\n");
printf(" -P, --pv Exit status 1 if not running as PV guest\n");
- printf(" -H, --hvm Exit status 1 if not running as HVM guest.\n");
+ printf(" -H, --hvm Exit status 1 if not running as HVM or PVH guest.\n");
printf(" -N, --none Exit status 1 if running on Xen (PV or HVM)\n");
}
+static bool check_dir(const char *filename)
+{
+ FILE *f;
+ struct stat stab;
+ bool res;
+
+ f = fopen(filename, "r");
+ if ( !f )
+ return false;
+ res = !fstat(fileno(f), &stab) && S_ISDIR(stab.st_mode);
+ fclose(f);
+
+ return res;
+}
+
+static char *read_file_content(const char *filename)
+{
+ FILE *f;
+ struct stat stab;
+ char *content = NULL;
+ int datalen;
+
+ f = fopen(filename, "r");
+ if ( !f )
+ return NULL;
+
+ if ( fstat(fileno(f), &stab) || !S_ISREG(stab.st_mode) ||
+ stab.st_size > INT_MAX || !stab.st_size )
+ goto out;
+
+ content = malloc(stab.st_size + 1);
+ if ( !content )
+ goto out;
+
+ /* For sysfs file, datalen is always PAGE_SIZE. 'read'
+ * will return the number of bytes of the actual content,
+ * rs <= datalen is expected.
+ */
+ datalen = fread(content, 1, stab.st_size, f);
+ content[datalen] = 0;
+ if ( ferror(f) )
+ {
+ free(content);
+ content = NULL;
+ }
+
+ out:
+ fclose(f);
+ return content;
+}
+
+static enum guest_type check_sysfs(void)
+{
+ char *str, *tmp;
+ enum guest_type res = XEN_NONE;
+
+ if ( !check_dir("/sys/hypervisor") )
+ return 0;
+
+ str = read_file_content("/sys/hypervisor/type");
+ if ( !str || strcmp(str, "xen\n") )
+ goto out;
+ free(str);
+
+ str = read_file_content("/sys/hypervisor/guest_type");
+ if ( !str )
+ return 0;
+ str[strlen(str) - 1] = 0;
+ type = str;
+ if ( !strcmp(type, "PV") )
+ res = XEN_PV;
+ else
+ res = XEN_HVM;
+
+ str = read_file_content("/sys/hypervisor/version/major");
+ if ( str )
+ str[strlen(str) - 1] = 0;
+ tmp = read_file_content("/sys/hypervisor/version/minor");
+ if ( tmp )
+ tmp[strlen(tmp) - 1] = 0;
+ if ( str && tmp )
+ asprintf(&ver, "V%s.%s", str, tmp);
+ else
+ ver = strdup("unknown version");
+ free(tmp);
+
+ out:
+ free(str);
+ return res;
+}
+
int main(int argc, char **argv)
{
- enum { XEN_PV = 1, XEN_HVM = 2, XEN_NONE = 3 } detected = 0, expected = 0;
- uint32_t version = 0;
+ enum guest_type detected, expected = 0;
int ch, quiet = 0;
const static char sopts[] = "hqPHN";
@@ -133,9 +240,14 @@ int main(int argc, char **argv)
}
}
+ detected = check_sysfs();
+ if ( detected )
+ goto out;
+
/* Check for execution in HVM context. */
detected = XEN_HVM;
- if ( (version = check_for_xen(0)) != 0 )
+ type = "HVM";
+ if ( check_for_xen(0) )
goto out;
/*
@@ -144,9 +256,10 @@ int main(int argc, char **argv)
* will longjmp via the signal handler, and print "Not running on Xen".
*/
detected = XEN_PV;
+ type = "PV";
if ( !setjmp(sigill_jmp)
&& (signal(SIGILL, sigill_handler) != SIG_ERR)
- && ((version = check_for_xen(1)) != 0) )
+ && check_for_xen(1) )
goto out;
detected = XEN_NONE;
@@ -157,9 +270,9 @@ int main(int argc, char **argv)
else if ( detected == XEN_NONE )
printf("Not running on Xen.\n");
else
- printf("Running in %s context on Xen v%d.%d.\n",
- (detected == XEN_PV) ? "PV" : "HVM",
- (uint16_t)(version >> 16), (uint16_t)version);
+ printf("Running in %s context on Xen %s.\n", type, ver);
+
+ free(ver);
return expected && (expected != detected);
}
--
2.12.3
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
2017-06-15 9:58 [PATCH] tools/xen-detect: try sysfs node for obtaining guest type Juergen Gross
@ 2017-06-20 11:05 ` Wei Liu
2017-06-21 14:24 ` Olaf Hering
1 sibling, 0 replies; 6+ messages in thread
From: Wei Liu @ 2017-06-20 11:05 UTC (permalink / raw)
To: Juergen Gross; +Cc: xen-devel, ian.jackson, wei.liu2
On Thu, Jun 15, 2017 at 11:58:27AM +0200, Juergen Gross wrote:
> Instead of relying on cpuid instruction behaviour to tell which domain
> type we are just try asking the kernel via the appropriate sysfs node
> (added in Linux kernel 4.13).
>
> Keep the old detection logic as a fallback for older kernels.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
I only skim-read this patch. I agree with the general approach.
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
2017-06-15 9:58 [PATCH] tools/xen-detect: try sysfs node for obtaining guest type Juergen Gross
2017-06-20 11:05 ` Wei Liu
@ 2017-06-21 14:24 ` Olaf Hering
2017-06-21 14:27 ` Wei Liu
1 sibling, 1 reply; 6+ messages in thread
From: Olaf Hering @ 2017-06-21 14:24 UTC (permalink / raw)
To: Juergen Gross; +Cc: xen-devel, wei.liu2, ian.jackson
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On Thu, Jun 15, Juergen Gross wrote:
> +++ b/tools/misc/xen-detect.c
> + asprintf(&ver, "V%u.%u",
> + (uint16_t)(regs[0] >> 16), (uint16_t)regs[0]);
> + asprintf(&ver, "V%s.%s", str, tmp);
This fails to build:
xen-detect.c:196:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
xen-detect.c:93:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
Olaf
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
2017-06-21 14:24 ` Olaf Hering
@ 2017-06-21 14:27 ` Wei Liu
2017-06-21 14:32 ` Olaf Hering
2017-06-21 15:00 ` Ian Jackson
0 siblings, 2 replies; 6+ messages in thread
From: Wei Liu @ 2017-06-21 14:27 UTC (permalink / raw)
To: Olaf Hering; +Cc: Juergen Gross, xen-devel, wei.liu2, ian.jackson
On Wed, Jun 21, 2017 at 04:24:33PM +0200, Olaf Hering wrote:
> On Thu, Jun 15, Juergen Gross wrote:
>
> > +++ b/tools/misc/xen-detect.c
>
> > + asprintf(&ver, "V%u.%u",
> > + (uint16_t)(regs[0] >> 16), (uint16_t)regs[0]);
>
> > + asprintf(&ver, "V%s.%s", str, tmp);
>
> This fails to build:
>
> xen-detect.c:196:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
> xen-detect.c:93:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
Hmm... your gcc seems to be rather strict. :-)
>
> Olaf
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
2017-06-21 14:27 ` Wei Liu
@ 2017-06-21 14:32 ` Olaf Hering
2017-06-21 15:00 ` Ian Jackson
1 sibling, 0 replies; 6+ messages in thread
From: Olaf Hering @ 2017-06-21 14:32 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, xen-devel, ian.jackson
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On Wed, Jun 21, Wei Liu wrote:
> Hmm... your gcc seems to be rather strict. :-)
Yes, all of them:
https://build.opensuse.org/package/show/home:olh:xen-unstable/xen
All red. :-)
Olaf
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tools/xen-detect: try sysfs node for obtaining guest type
2017-06-21 14:27 ` Wei Liu
2017-06-21 14:32 ` Olaf Hering
@ 2017-06-21 15:00 ` Ian Jackson
1 sibling, 0 replies; 6+ messages in thread
From: Ian Jackson @ 2017-06-21 15:00 UTC (permalink / raw)
To: Wei Liu; +Cc: Juergen Gross, xen-devel, Olaf Hering
Wei Liu writes ("Re: [Xen-devel] [PATCH] tools/xen-detect: try sysfs node for obtaining guest type"):
> On Wed, Jun 21, 2017 at 04:24:33PM +0200, Olaf Hering wrote:
> > On Thu, Jun 15, Juergen Gross wrote:
> > > +++ b/tools/misc/xen-detect.c
> >
> > > + asprintf(&ver, "V%u.%u",
> > > + (uint16_t)(regs[0] >> 16), (uint16_t)regs[0]);
> >
> > > + asprintf(&ver, "V%s.%s", str, tmp);
> >
> > This fails to build:
> >
> > xen-detect.c:196:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
> > xen-detect.c:93:17: error: ignoring return value of 'asprintf', declared with attribute warn_unused_result [-Werror=unused-result]
>
> Hmm... your gcc seems to be rather strict. :-)
gcc is correct.
asprintf can fail if its malloc fails.
Ian.
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2017-06-15 9:58 [PATCH] tools/xen-detect: try sysfs node for obtaining guest type Juergen Gross
2017-06-20 11:05 ` Wei Liu
2017-06-21 14:24 ` Olaf Hering
2017-06-21 14:27 ` Wei Liu
2017-06-21 14:32 ` Olaf Hering
2017-06-21 15:00 ` Ian Jackson
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