| Message ID | 20240131112600.121482-1-kjain@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/hv-gpci: Fix the hcall return value checks in single_gpci_request function | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 6 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 23 jobs. |
On 31/01/24 4:56 pm, Kajol Jain wrote: > Running event hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > in one of the system throws below error: > > ---Logs--- > # perf list | grep hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles > hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=?/[Kernel PMU event] > > > # perf stat -v -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 > Using CPUID 00800200 > Control descriptor is not initialized > Warning: > hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event is not supported by the kernel. > failed to read counter hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > > Performance counter stats for 'system wide': > > <not supported> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > > 2.000700771 seconds time elapsed > > The above error is because of the hcall failure as required > permission "Enable Performance Information Collection" is not set. > Based on current code, single_gpci_request function did not check the > error type incase hcall fails and by default returns EINVAL. But we can > have other reasons for hcall failures like H_AUTHORITY/H_PARAMETER for which > we need to act accordingly. > Fix this issue by adding new checks in the single_gpci_request function. > > Result after fix patch changes: > > # perf stat -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 > Error: > No permission to enable hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event. > > Fixes: 220a0c609ad1 ("powerpc/perf: Add support for the hv gpci (get performance counter info) interface") > Reported-by: Akanksha J N <akanksha@linux.ibm.com> > Signed-off-by: Kajol Jain <kjain@linux.ibm.com> Tested the patch on Power10 system, and the fix works fine. # ./perf stat -v -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=1/ sleep 2 Control descriptor is not initialized hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=1/: 0 2001246376 2001246376 Performance counter stats for 'system wide': 0 hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=1/ 2.001250313 seconds time elapsed Tested-by: Akanksha J N <akanksha@linux.ibm.com> > --- > arch/powerpc/perf/hv-gpci.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c > index 27f18119fda1..101060facd81 100644 > --- a/arch/powerpc/perf/hv-gpci.c > +++ b/arch/powerpc/perf/hv-gpci.c > @@ -695,7 +695,17 @@ static unsigned long single_gpci_request(u32 req, u32 starting_index, > > ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO, > virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE); > - if (ret) { > + > + /* > + * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', > + * which means that the current buffer size cannot accommodate > + * all the information and a partial buffer returned. > + * Since in this function we are only accessing data for a given starting index, > + * we don't need to accommodate whole data and can get required count by > + * accessing very first entry. > + * Hence hcall fails only incase the ret value is other than H_SUCCESS or H_PARAMETER. > + */ > + if (ret && (ret != H_PARAMETER)) { > pr_devel("hcall failed: 0x%lx\n", ret); > goto out; > } > @@ -724,7 +734,7 @@ static u64 h_gpci_get_value(struct perf_event *event) > event_get_offset(event), > event_get_length(event), > &count); > - if (ret) > + if (ret && (ret != H_PARAMETER)) > return 0; > return count; > } > @@ -759,6 +769,7 @@ static int h_gpci_event_init(struct perf_event *event) > { > u64 count; > u8 length; > + unsigned long ret; > > /* Not our event */ > if (event->attr.type != event->pmu->type) > @@ -789,13 +800,23 @@ static int h_gpci_event_init(struct perf_event *event) > } > > /* check if the request works... */ > - if (single_gpci_request(event_get_request(event), > + ret = single_gpci_request(event_get_request(event), > event_get_starting_index(event), > event_get_secondary_index(event), > event_get_counter_info_version(event), > event_get_offset(event), > length, > - &count)) { > + &count); > + > + /* > + * ret value as H_AUTHORITY implies that partition is not permitted to retrieve > + * performance information, and required to set > + * "Enable Performance Information Collection" option. > + */ > + if (ret == H_AUTHORITY) > + return -EPERM; > + > + if (ret && (ret != H_PARAMETER)) { > pr_devel("gpci hcall failed\n"); > return -EINVAL; > }
Kajol Jain <kjain@linux.ibm.com> writes: > Running event hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > in one of the system throws below error: > > ---Logs--- > # perf list | grep hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles > hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=?/[Kernel PMU event] > > > # perf stat -v -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 > Using CPUID 00800200 > Control descriptor is not initialized > Warning: > hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event is not supported by the kernel. > failed to read counter hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > > Performance counter stats for 'system wide': > > <not supported> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ > > 2.000700771 seconds time elapsed > > The above error is because of the hcall failure as required > permission "Enable Performance Information Collection" is not set. > Based on current code, single_gpci_request function did not check the > error type incase hcall fails and by default returns EINVAL. But we can > have other reasons for hcall failures like H_AUTHORITY/H_PARAMETER for which > we need to act accordingly. > Fix this issue by adding new checks in the single_gpci_request function. > > Result after fix patch changes: > > # perf stat -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 > Error: > No permission to enable hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event. > > Fixes: 220a0c609ad1 ("powerpc/perf: Add support for the hv gpci (get performance counter info) interface") > Reported-by: Akanksha J N <akanksha@linux.ibm.com> > Signed-off-by: Kajol Jain <kjain@linux.ibm.com> > --- > arch/powerpc/perf/hv-gpci.c | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c > index 27f18119fda1..101060facd81 100644 > --- a/arch/powerpc/perf/hv-gpci.c > +++ b/arch/powerpc/perf/hv-gpci.c > @@ -695,7 +695,17 @@ static unsigned long single_gpci_request(u32 req, u32 starting_index, > > ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO, > virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE); > - if (ret) { > + > + /* > + * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', Don't we expect H_PARAMETER if any parameter value is incorrect? > + * which means that the current buffer size cannot accommodate > + * all the information and a partial buffer returned. I don't see how we can infer that H_PARAMETER means the buffer is too small and accessing the first entry is OK? cheers > + * Since in this function we are only accessing data for a given starting index, > + * we don't need to accommodate whole data and can get required count by > + * accessing very first entry. > + * Hence hcall fails only incase the ret value is other than H_SUCCESS or H_PARAMETER. > + */ > + if (ret && (ret != H_PARAMETER)) { > pr_devel("hcall failed: 0x%lx\n", ret); > goto out; > }
On 2/20/24 18:08, Michael Ellerman wrote: > Kajol Jain <kjain@linux.ibm.com> writes: >> Running event hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ >> in one of the system throws below error: >> >> ---Logs--- >> # perf list | grep hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles >> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=?/[Kernel PMU event] >> >> >> # perf stat -v -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 >> Using CPUID 00800200 >> Control descriptor is not initialized >> Warning: >> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event is not supported by the kernel. >> failed to read counter hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ >> >> Performance counter stats for 'system wide': >> >> <not supported> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ >> >> 2.000700771 seconds time elapsed >> >> The above error is because of the hcall failure as required >> permission "Enable Performance Information Collection" is not set. >> Based on current code, single_gpci_request function did not check the >> error type incase hcall fails and by default returns EINVAL. But we can >> have other reasons for hcall failures like H_AUTHORITY/H_PARAMETER for which >> we need to act accordingly. >> Fix this issue by adding new checks in the single_gpci_request function. >> >> Result after fix patch changes: >> >> # perf stat -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 >> Error: >> No permission to enable hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event. >> >> Fixes: 220a0c609ad1 ("powerpc/perf: Add support for the hv gpci (get performance counter info) interface") >> Reported-by: Akanksha J N <akanksha@linux.ibm.com> >> Signed-off-by: Kajol Jain <kjain@linux.ibm.com> >> --- >> arch/powerpc/perf/hv-gpci.c | 29 +++++++++++++++++++++++++---- >> 1 file changed, 25 insertions(+), 4 deletions(-) >> >> diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c >> index 27f18119fda1..101060facd81 100644 >> --- a/arch/powerpc/perf/hv-gpci.c >> +++ b/arch/powerpc/perf/hv-gpci.c >> @@ -695,7 +695,17 @@ static unsigned long single_gpci_request(u32 req, u32 starting_index, >> >> ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO, >> virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE); >> - if (ret) { >> + >> + /* >> + * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', > > Don't we expect H_PARAMETER if any parameter value is incorrect? > >> + * which means that the current buffer size cannot accommodate >> + * all the information and a partial buffer returned. > > I don't see how we can infer that H_PARAMETER means the buffer is too > small and accessing the first entry is OK? Hi Michael, Based on getCounterInfo documentation and the name convention it uses, we actually used H_PARAMETER to specify the buffer issue incase buffer cannot accommodate all the data. Hence we are using that return value in the check. Since based on hv-gpci event counter we only want data for specific starting index and the hv-gpci hcall actually store data starting from given starting index in the result buffer. We can ensure that accessing first entry will be enough. Thanks, Kajol Jain > > cheers > >> + * Since in this function we are only accessing data for a given starting index, >> + * we don't need to accommodate whole data and can get required count by >> + * accessing very first entry. >> + * Hence hcall fails only incase the ret value is other than H_SUCCESS or H_PARAMETER. >> + */ >> + if (ret && (ret != H_PARAMETER)) { >> pr_devel("hcall failed: 0x%lx\n", ret); >> goto out; >> }
diff --git a/arch/powerpc/perf/hv-gpci.c b/arch/powerpc/perf/hv-gpci.c index 27f18119fda1..101060facd81 100644 --- a/arch/powerpc/perf/hv-gpci.c +++ b/arch/powerpc/perf/hv-gpci.c @@ -695,7 +695,17 @@ static unsigned long single_gpci_request(u32 req, u32 starting_index, ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO, virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE); - if (ret) { + + /* + * ret value as 'H_PARAMETER' corresponds to 'GEN_BUF_TOO_SMALL', + * which means that the current buffer size cannot accommodate + * all the information and a partial buffer returned. + * Since in this function we are only accessing data for a given starting index, + * we don't need to accommodate whole data and can get required count by + * accessing very first entry. + * Hence hcall fails only incase the ret value is other than H_SUCCESS or H_PARAMETER. + */ + if (ret && (ret != H_PARAMETER)) { pr_devel("hcall failed: 0x%lx\n", ret); goto out; } @@ -724,7 +734,7 @@ static u64 h_gpci_get_value(struct perf_event *event) event_get_offset(event), event_get_length(event), &count); - if (ret) + if (ret && (ret != H_PARAMETER)) return 0; return count; } @@ -759,6 +769,7 @@ static int h_gpci_event_init(struct perf_event *event) { u64 count; u8 length; + unsigned long ret; /* Not our event */ if (event->attr.type != event->pmu->type) @@ -789,13 +800,23 @@ static int h_gpci_event_init(struct perf_event *event) } /* check if the request works... */ - if (single_gpci_request(event_get_request(event), + ret = single_gpci_request(event_get_request(event), event_get_starting_index(event), event_get_secondary_index(event), event_get_counter_info_version(event), event_get_offset(event), length, - &count)) { + &count); + + /* + * ret value as H_AUTHORITY implies that partition is not permitted to retrieve + * performance information, and required to set + * "Enable Performance Information Collection" option. + */ + if (ret == H_AUTHORITY) + return -EPERM; + + if (ret && (ret != H_PARAMETER)) { pr_devel("gpci hcall failed\n"); return -EINVAL; }
Running event hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ in one of the system throws below error: ---Logs--- # perf list | grep hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=?/[Kernel PMU event] # perf stat -v -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 Using CPUID 00800200 Control descriptor is not initialized Warning: hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event is not supported by the kernel. failed to read counter hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ Performance counter stats for 'system wide': <not supported> hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ 2.000700771 seconds time elapsed The above error is because of the hcall failure as required permission "Enable Performance Information Collection" is not set. Based on current code, single_gpci_request function did not check the error type incase hcall fails and by default returns EINVAL. But we can have other reasons for hcall failures like H_AUTHORITY/H_PARAMETER for which we need to act accordingly. Fix this issue by adding new checks in the single_gpci_request function. Result after fix patch changes: # perf stat -e hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ sleep 2 Error: No permission to enable hv_gpci/dispatch_timebase_by_processor_processor_time_in_timebase_cycles,phys_processor_idx=0/ event. Fixes: 220a0c609ad1 ("powerpc/perf: Add support for the hv gpci (get performance counter info) interface") Reported-by: Akanksha J N <akanksha@linux.ibm.com> Signed-off-by: Kajol Jain <kjain@linux.ibm.com> --- arch/powerpc/perf/hv-gpci.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-)