Merge tag 'powerpc-4.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux

Pull powerpc updates from Michael Ellerman:

 - Numerous minor fixes, cleanups etc.

 - More EEH work from Gavin to remove its dependency on device_nodes.

 - Memory hotplug implemented entirely in the kernel from Nathan
   Fontenot.

 - Removal of redundant CONFIG_PPC_OF by Kevin Hao.

 - Rewrite of VPHN parsing logic & tests from Greg Kurz.

 - A fix from Nish Aravamudan to reduce memory usage by clamping
   nodes_possible_map.

 - Support for pstore on powernv from Hari Bathini.

 - Removal of old powerpc specific byte swap routines by David Gibson.

 - Fix from Vasant Hegde to prevent the flash driver telling you it was
   flashing your firmware when it wasn't.

 - Patch from Ben Herrenschmidt to add an OPAL heartbeat driver.

 - Fix for an oops causing get/put_cpu_var() imbalance in perf by Jan
   Stancek.

 - Some fixes for migration from Tyrel Datwyler.

 - A new syscall to switch the cpu endian by Michael Ellerman.

 - Large series from Wei Yang to implement SRIOV, reviewed and acked by
   Bjorn.

 - A fix for the OPAL sensor driver from Cédric Le Goater.

 - Fixes to get STRICT_MM_TYPECHECKS building again by Michael Ellerman.

 - Large series from Daniel Axtens to make our PCI hooks per PHB rather
   than per machine.

 - Small patch from Sam Bobroff to explicitly abort non-suspended
   transactions on syscalls, plus a test to exercise it.

 - Numerous reworks and fixes for the 24x7 PMU from Sukadev Bhattiprolu.

 - Small patch to enable the hard lockup detector from Anton Blanchard.

 - Fix from Dave Olson for missing L2 cache information on some CPUs.

 - Some fixes from Michael Ellerman to get Cell machines booting again.

 - Freescale updates from Scott: Highlights include BMan device tree
   nodes, an MSI erratum workaround, a couple minor performance
   improvements, config updates, and misc fixes/cleanup.

* tag 'powerpc-4.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux: (196 commits)
  powerpc/powermac: Fix build error seen with powermac smp builds
  powerpc/pseries: Fix compile of memory hotplug without CONFIG_MEMORY_HOTREMOVE
  powerpc: Remove PPC32 code from pseries specific find_and_init_phbs()
  powerpc/cell: Fix iommu breakage caused by controller_ops change
  powerpc/eeh: Fix crash in eeh_add_device_early() on Cell
  powerpc/perf: Cap 64bit userspace backtraces to PERF_MAX_STACK_DEPTH
  powerpc/perf/hv-24x7: Fail 24x7 initcall if create_events_from_catalog() fails
  powerpc/pseries: Correct memory hotplug locking
  powerpc: Fix missing L2 cache size in /sys/devices/system/cpu
  powerpc: Add ppc64 hard lockup detector support
  oprofile: Disable oprofile NMI timer on ppc64
  powerpc/perf/hv-24x7: Add missing put_cpu_var()
  powerpc/perf/hv-24x7: Break up single_24x7_request
  powerpc/perf/hv-24x7: Define update_event_count()
  powerpc/perf/hv-24x7: Whitespace cleanup
  powerpc/perf/hv-24x7: Define add_event_to_24x7_request()
  powerpc/perf/hv-24x7: Rename hv_24x7_event_update
  powerpc/perf/hv-24x7: Move debug prints to separate function
  powerpc/perf/hv-24x7: Drop event_24x7_request()
  powerpc/perf/hv-24x7: Use pr_devel() to log message
  ...

Conflicts:
	tools/testing/selftests/powerpc/Makefile
	tools/testing/selftests/powerpc/tm/Makefile

4 files changed, 172 insertions, 93 deletions

diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index 2396dda282cd..ead55351b254 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -243,7 +243,7 @@ static void perf_callchain_user_64(struct perf_callchain_entry *entry,
         sp = regs->gpr[1];
         perf_callchain_store(entry, next_ip);
 
-        for (;;) {
+        while (entry->nr < PERF_MAX_STACK_DEPTH) {
                 fp = (unsigned long __user *) sp;
                 if (!valid_user_sp(sp, 1) || read_user_stack_64(fp, &next_sp))
                         return;
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 7fd60dcb2cb0..12b638425bb9 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1837,8 +1837,10 @@ static int power_pmu_event_init(struct perf_event *event)
                 cpuhw->bhrb_filter = ppmu->bhrb_filter_map(
                                         event->attr.branch_sample_type);
 
-                if(cpuhw->bhrb_filter == -1)
+                if (cpuhw->bhrb_filter == -1) {
+                        put_cpu_var(cpu_hw_events);
                         return -EOPNOTSUPP;
+                }
         }
 
         put_cpu_var(cpu_hw_events);
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index abeb9ec0d117..ec2eb20631d1 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -142,6 +142,15 @@ static struct attribute_group event_long_desc_group = {
 
 static struct kmem_cache *hv_page_cache;
 
+/*
+ * request_buffer and result_buffer are not required to be 4k aligned,
+ * but are not allowed to cross any 4k boundary. Aligning them to 4k is
+ * the simplest way to ensure that.
+ */
+#define H24x7_DATA_BUFFER_SIZE  4096
+DEFINE_PER_CPU(char, hv_24x7_reqb[H24x7_DATA_BUFFER_SIZE]) __aligned(4096);
+DEFINE_PER_CPU(char, hv_24x7_resb[H24x7_DATA_BUFFER_SIZE]) __aligned(4096);
+
 static char *event_name(struct hv_24x7_event_data *ev, int *len)
 {
         *len = be16_to_cpu(ev->event_name_len) - 2;
@@ -152,6 +161,7 @@ static char *event_desc(struct hv_24x7_event_data *ev, int *len)
 {
         unsigned nl = be16_to_cpu(ev->event_name_len);
         __be16 *desc_len = (__be16 *)(ev->remainder + nl - 2);
+
         *len = be16_to_cpu(*desc_len) - 2;
         return (char *)ev->remainder + nl;
 }
@@ -162,6 +172,7 @@ static char *event_long_desc(struct hv_24x7_event_data *ev, int *len)
         __be16 *desc_len_ = (__be16 *)(ev->remainder + nl - 2);
         unsigned desc_len = be16_to_cpu(*desc_len_);
         __be16 *long_desc_len = (__be16 *)(ev->remainder + nl + desc_len - 2);
+
         *len = be16_to_cpu(*long_desc_len) - 2;
         return (char *)ev->remainder + nl + desc_len;
 }
@@ -239,14 +250,12 @@ static unsigned long h_get_24x7_catalog_page_(unsigned long phys_4096,
                                               unsigned long index)
 {
         pr_devel("h_get_24x7_catalog_page(0x%lx, %lu, %lu)",
-                        phys_4096,
-                        version,
-                        index);
+                        phys_4096, version, index);
+
         WARN_ON(!IS_ALIGNED(phys_4096, 4096));
+
         return plpar_hcall_norets(H_GET_24X7_CATALOG_PAGE,
-                        phys_4096,
-                        version,
-                        index);
+                        phys_4096, version, index);
 }
 
 static unsigned long h_get_24x7_catalog_page(char page[],
@@ -300,6 +309,7 @@ static ssize_t device_show_string(struct device *dev,
         struct dev_ext_attribute *d;
 
         d = container_of(attr, struct dev_ext_attribute, attr);
+
         return sprintf(buf, "%s\n", (char *)d->var);
 }
 
@@ -314,6 +324,7 @@ static struct attribute *device_str_attr_create_(char *name, char *str)
         attr->attr.attr.name = name;
         attr->attr.attr.mode = 0444;
         attr->attr.show = device_show_string;
+
         return &attr->attr.attr;
 }
 
@@ -387,7 +398,6 @@ static struct attribute *event_to_attr(unsigned ix,
                 a_ev_name = kasprintf(GFP_KERNEL, "%.*s%s__%d",
                                 (int)event_name_len, ev_name, ev_suffix, nonce);
 
-
         if (!a_ev_name)
                 goto out_val;
 
@@ -637,7 +647,7 @@ static ssize_t catalog_event_len_validate(struct hv_24x7_event_data *event,
 
 #define MAX_4K (SIZE_MAX / 4096)
 
-static void create_events_from_catalog(struct attribute ***events_,
+static int create_events_from_catalog(struct attribute ***events_,
                 struct attribute ***event_descs_,
                 struct attribute ***event_long_descs_)
 {
@@ -655,19 +665,25 @@ static void create_events_from_catalog(struct attribute ***events_,
         void *event_data, *end;
         struct hv_24x7_event_data *event;
         struct rb_root ev_uniq = RB_ROOT;
+        int ret = 0;
 
-        if (!page)
+        if (!page) {
+                ret = -ENOMEM;
                 goto e_out;
+        }
 
         hret = h_get_24x7_catalog_page(page, 0, 0);
-        if (hret)
+        if (hret) {
+                ret = -EIO;
                 goto e_free;
+        }
 
         catalog_version_num = be64_to_cpu(page_0->version);
         catalog_page_len = be32_to_cpu(page_0->length);
 
         if (MAX_4K < catalog_page_len) {
                 pr_err("invalid page count: %zu\n", catalog_page_len);
+                ret = -EIO;
                 goto e_free;
         }
 
@@ -686,6 +702,7 @@ static void create_events_from_catalog(struct attribute ***events_,
                         || (MAX_4K - event_data_offs < event_data_len)) {
                 pr_err("invalid event data offs %zu and/or len %zu\n",
                                 event_data_offs, event_data_len);
+                ret = -EIO;
                 goto e_free;
         }
 
@@ -694,12 +711,14 @@ static void create_events_from_catalog(struct attribute ***events_,
                                 event_data_offs,
                                 event_data_offs + event_data_len,
                                 catalog_page_len);
+                ret = -EIO;
                 goto e_free;
         }
 
         if (SIZE_MAX / MAX_EVENTS_PER_EVENT_DATA - 1 < event_entry_count) {
                 pr_err("event_entry_count %zu is invalid\n",
                                 event_entry_count);
+                ret = -EIO;
                 goto e_free;
         }
 
@@ -712,6 +731,7 @@ static void create_events_from_catalog(struct attribute ***events_,
         event_data = vmalloc(event_data_bytes);
         if (!event_data) {
                 pr_err("could not allocate event data\n");
+                ret = -ENOMEM;
                 goto e_free;
         }
 
@@ -731,6 +751,7 @@ static void create_events_from_catalog(struct attribute ***events_,
                 if (hret) {
                         pr_err("failed to get event data in page %zu\n",
                                         i + event_data_offs);
+                        ret = -EIO;
                         goto e_event_data;
                 }
         }
@@ -778,18 +799,24 @@ static void create_events_from_catalog(struct attribute ***events_,
                                 event_idx_last, event_entry_count, junk_events);
 
         events = kmalloc_array(attr_max + 1, sizeof(*events), GFP_KERNEL);
-        if (!events)
+        if (!events) {
+                ret = -ENOMEM;
                 goto e_event_data;
+        }
 
         event_descs = kmalloc_array(event_idx + 1, sizeof(*event_descs),
                                 GFP_KERNEL);
-        if (!event_descs)
+        if (!event_descs) {
+                ret = -ENOMEM;
                 goto e_event_attrs;
+        }
 
         event_long_descs = kmalloc_array(event_idx + 1,
                         sizeof(*event_long_descs), GFP_KERNEL);
-        if (!event_long_descs)
+        if (!event_long_descs) {
+                ret = -ENOMEM;
                 goto e_event_descs;
+        }
 
         /* Iterate over the catalog filling in the attribute vector */
         for (junk_events = 0, event_attr_ct = 0, desc_ct = 0, long_desc_ct = 0,
@@ -843,7 +870,7 @@ static void create_events_from_catalog(struct attribute ***events_,
         *events_ = events;
         *event_descs_ = event_descs;
         *event_long_descs_ = event_long_descs;
-        return;
+        return 0;
 
 e_event_descs:
         kfree(event_descs);
@@ -857,6 +884,7 @@ e_out:
         *events_ = NULL;
         *event_descs_ = NULL;
         *event_long_descs_ = NULL;
+        return ret;
 }
 
 static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
@@ -872,6 +900,7 @@ static ssize_t catalog_read(struct file *filp, struct kobject *kobj,
         uint64_t catalog_version_num = 0;
         void *page = kmem_cache_alloc(hv_page_cache, GFP_USER);
         struct hv_24x7_catalog_page_0 *page_0 = page;
+
         if (!page)
                 return -ENOMEM;
 
@@ -976,31 +1005,104 @@ static const struct attribute_group *attr_groups[] = {
         NULL,
 };
 
-DEFINE_PER_CPU(char, hv_24x7_reqb[4096]) __aligned(4096);
-DEFINE_PER_CPU(char, hv_24x7_resb[4096]) __aligned(4096);
+static void log_24x7_hcall(struct hv_24x7_request_buffer *request_buffer,
+                        struct hv_24x7_data_result_buffer *result_buffer,
+                        unsigned long ret)
+{
+        struct hv_24x7_request *req;
+
+        req = &request_buffer->requests[0];
+        pr_notice_ratelimited("hcall failed: [%d %#x %#x %d] => "
+                        "ret 0x%lx (%ld) detail=0x%x failing ix=%x\n",
+                        req->performance_domain, req->data_offset,
+                        req->starting_ix, req->starting_lpar_ix, ret, ret,
+                        result_buffer->detailed_rc,
+                        result_buffer->failing_request_ix);
+}
+
+/*
+ * Start the process for a new H_GET_24x7_DATA hcall.
+ */
+static void init_24x7_request(struct hv_24x7_request_buffer *request_buffer,
+                        struct hv_24x7_data_result_buffer *result_buffer)
+{
+
+        memset(request_buffer, 0, 4096);
+        memset(result_buffer, 0, 4096);
+
+        request_buffer->interface_version = HV_24X7_IF_VERSION_CURRENT;
+        /* memset above set request_buffer->num_requests to 0 */
+}
 
-static unsigned long single_24x7_request(u8 domain, u32 offset, u16 ix,
-                                         u16 lpar, u64 *res,
-                                         bool success_expected)
+/*
+ * Commit (i.e perform) the H_GET_24x7_DATA hcall using the data collected
+ * by 'init_24x7_request()' and 'add_event_to_24x7_request()'.
+ */
+static int make_24x7_request(struct hv_24x7_request_buffer *request_buffer,
+                        struct hv_24x7_data_result_buffer *result_buffer)
 {
         unsigned long ret;
 
         /*
-         * request_buffer and result_buffer are not required to be 4k aligned,
-         * but are not allowed to cross any 4k boundary. Aligning them to 4k is
-         * the simplest way to ensure that.
+         * NOTE: Due to variable number of array elements in request and
+         *       result buffer(s), sizeof() is not reliable. Use the actual
+         *       allocated buffer size, H24x7_DATA_BUFFER_SIZE.
          */
-        struct reqb {
-                struct hv_24x7_request_buffer buf;
-                struct hv_24x7_request req;
-        } __packed *request_buffer;
-
-        struct {
-                struct hv_24x7_data_result_buffer buf;
-                struct hv_24x7_result res;
-                struct hv_24x7_result_element elem;
-                __be64 result;
-        } __packed *result_buffer;
+        ret = plpar_hcall_norets(H_GET_24X7_DATA,
+                        virt_to_phys(request_buffer), H24x7_DATA_BUFFER_SIZE,
+                        virt_to_phys(result_buffer),  H24x7_DATA_BUFFER_SIZE);
+
+        if (ret)
+                log_24x7_hcall(request_buffer, result_buffer, ret);
+
+        return ret;
+}
+
+/*
+ * Add the given @event to the next slot in the 24x7 request_buffer.
+ *
+ * Note that H_GET_24X7_DATA hcall allows reading several counters'
+ * values in a single HCALL. We expect the caller to add events to the
+ * request buffer one by one, make the HCALL and process the results.
+ */
+static int add_event_to_24x7_request(struct perf_event *event,
+                                struct hv_24x7_request_buffer *request_buffer)
+{
+        u16 idx;
+        int i;
+        struct hv_24x7_request *req;
+
+        if (request_buffer->num_requests > 254) {
+                pr_devel("Too many requests for 24x7 HCALL %d\n",
+                                request_buffer->num_requests);
+                return -EINVAL;
+        }
+
+        if (is_physical_domain(event_get_domain(event)))
+                idx = event_get_core(event);
+        else
+                idx = event_get_vcpu(event);
+
+        i = request_buffer->num_requests++;
+        req = &request_buffer->requests[i];
+
+        req->performance_domain = event_get_domain(event);
+        req->data_size = cpu_to_be16(8);
+        req->data_offset = cpu_to_be32(event_get_offset(event));
+        req->starting_lpar_ix = cpu_to_be16(event_get_lpar(event)),
+        req->max_num_lpars = cpu_to_be16(1);
+        req->starting_ix = cpu_to_be16(idx);
+        req->max_ix = cpu_to_be16(1);
+
+        return 0;
+}
+
+static unsigned long single_24x7_request(struct perf_event *event, u64 *count)
+{
+        unsigned long ret;
+        struct hv_24x7_request_buffer *request_buffer;
+        struct hv_24x7_data_result_buffer *result_buffer;
+        struct hv_24x7_result *resb;
 
         BUILD_BUG_ON(sizeof(*request_buffer) > 4096);
         BUILD_BUG_ON(sizeof(*result_buffer) > 4096);
@@ -1008,63 +1110,28 @@ static unsigned long single_24x7_request(u8 domain, u32 offset, u16 ix,
         request_buffer = (void *)get_cpu_var(hv_24x7_reqb);
         result_buffer = (void *)get_cpu_var(hv_24x7_resb);
 
-        memset(request_buffer, 0, 4096);
-        memset(result_buffer, 0, 4096);
-
-        *request_buffer = (struct reqb) {
-                .buf = {
-                        .interface_version = HV_24X7_IF_VERSION_CURRENT,
-                        .num_requests = 1,
-                },
-                .req = {
-                        .performance_domain = domain,
-                        .data_size = cpu_to_be16(8),
-                        .data_offset = cpu_to_be32(offset),
-                        .starting_lpar_ix = cpu_to_be16(lpar),
-                        .max_num_lpars = cpu_to_be16(1),
-                        .starting_ix = cpu_to_be16(ix),
-                        .max_ix = cpu_to_be16(1),
-                }
-        };
+        init_24x7_request(request_buffer, result_buffer);
 
-        ret = plpar_hcall_norets(H_GET_24X7_DATA,
-                        virt_to_phys(request_buffer), sizeof(*request_buffer),
-                        virt_to_phys(result_buffer),  sizeof(*result_buffer));
+        ret = add_event_to_24x7_request(event, request_buffer);
+        if (ret)
+                goto out;
 
+        ret = make_24x7_request(request_buffer, result_buffer);
         if (ret) {
-                if (success_expected)
-                        pr_err_ratelimited("hcall failed: %d %#x %#x %d => "
-                                "0x%lx (%ld) detail=0x%x failing ix=%x\n",
-                                domain, offset, ix, lpar, ret, ret,
-                                result_buffer->buf.detailed_rc,
-                                result_buffer->buf.failing_request_ix);
+                log_24x7_hcall(request_buffer, result_buffer, ret);
                 goto out;
         }
 
-        *res = be64_to_cpu(result_buffer->result);
+        /* process result from hcall */
+        resb = &result_buffer->results[0];
+        *count = be64_to_cpu(resb->elements[0].element_data[0]);
 
 out:
+        put_cpu_var(hv_24x7_reqb);
+        put_cpu_var(hv_24x7_resb);
         return ret;
 }
 
-static unsigned long event_24x7_request(struct perf_event *event, u64 *res,
-                bool success_expected)
-{
-        u16 idx;
-        unsigned domain = event_get_domain(event);
-
-        if (is_physical_domain(domain))
-                idx = event_get_core(event);
-        else
-                idx = event_get_vcpu(event);
-
-        return single_24x7_request(event_get_domain(event),
-                                event_get_offset(event),
-                                idx,
-                                event_get_lpar(event),
-                                res,
-                                success_expected);
-}
 
 static int h_24x7_event_init(struct perf_event *event)
 {
@@ -1133,7 +1200,7 @@ static int h_24x7_event_init(struct perf_event *event)
         }
 
         /* see if the event complains */
-        if (event_24x7_request(event, &ct, false)) {
+        if (single_24x7_request(event, &ct)) {
                 pr_devel("test hcall failed\n");
                 return -EIO;
         }
@@ -1145,7 +1212,7 @@ static u64 h_24x7_get_value(struct perf_event *event)
 {
         unsigned long ret;
         u64 ct;
-        ret = event_24x7_request(event, &ct, true);
+        ret = single_24x7_request(event, &ct);
         if (ret)
                 /* We checked this in event init, shouldn't fail here... */
                 return 0;
@@ -1153,15 +1220,22 @@ static u64 h_24x7_get_value(struct perf_event *event)
         return ct;
 }
 
-static void h_24x7_event_update(struct perf_event *event)
+static void update_event_count(struct perf_event *event, u64 now)
 {
         s64 prev;
-        u64 now;
-        now = h_24x7_get_value(event);
+
         prev = local64_xchg(&event->hw.prev_count, now);
         local64_add(now - prev, &event->count);
 }
 
+static void h_24x7_event_read(struct perf_event *event)
+{
+        u64 now;
+
+        now = h_24x7_get_value(event);
+        update_event_count(event, now);
+}
+
 static void h_24x7_event_start(struct perf_event *event, int flags)
 {
         if (flags & PERF_EF_RELOAD)
@@ -1170,7 +1244,7 @@ static void h_24x7_event_start(struct perf_event *event, int flags)
 
 static void h_24x7_event_stop(struct perf_event *event, int flags)
 {
-        h_24x7_event_update(event);
+        h_24x7_event_read(event);
 }
 
 static int h_24x7_event_add(struct perf_event *event, int flags)
@@ -1191,7 +1265,7 @@ static struct pmu h_24x7_pmu = {
         .del         = h_24x7_event_stop,
         .start       = h_24x7_event_start,
         .stop        = h_24x7_event_stop,
-        .read        = h_24x7_event_update,
+        .read        = h_24x7_event_read,
 };
 
 static int hv_24x7_init(void)
@@ -1219,10 +1293,13 @@ static int hv_24x7_init(void)
         /* sampling not supported */
         h_24x7_pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
 
-        create_events_from_catalog(&event_group.attrs,
+        r = create_events_from_catalog(&event_group.attrs,
                                    &event_desc_group.attrs,
                                    &event_long_desc_group.attrs);
 
+        if (r)
+                return r;
+
         r = perf_pmu_register(&h_24x7_pmu, h_24x7_pmu.name, -1);
         if (r)
                 return r;
diff --git a/arch/powerpc/perf/hv-24x7.h b/arch/powerpc/perf/hv-24x7.h
index 69cd4e690f58..0f9fa21a29f2 100644
--- a/arch/powerpc/perf/hv-24x7.h
+++ b/arch/powerpc/perf/hv-24x7.h
@@ -50,7 +50,7 @@ struct hv_24x7_request_buffer {
         __u8 interface_version;
         __u8 num_requests;
         __u8 reserved[0xE];
-        struct hv_24x7_request requests[];
+        struct hv_24x7_request requests[1];
 } __packed;
 
 struct hv_24x7_result_element {
@@ -66,7 +66,7 @@ struct hv_24x7_result_element {
         __be32 lpar_cfg_instance_id;
 
         /* size = @result_element_data_size of cointaining result. */
-        __u8 element_data[];
+        __u64 element_data[1];
 } __packed;
 
 struct hv_24x7_result {
@@ -87,7 +87,7 @@ struct hv_24x7_result {
         /* WARNING: only valid for first result element due to variable sizes
          *          of result elements */
         /* struct hv_24x7_result_element[@num_elements_returned] */
-        struct hv_24x7_result_element elements[];
+        struct hv_24x7_result_element elements[1];
 } __packed;
 
 struct hv_24x7_data_result_buffer {
@@ -103,7 +103,7 @@ struct hv_24x7_data_result_buffer {
         __u8 reserved2[0x8];
         /* WARNING: only valid for the first result due to variable sizes of
          *          results */
-        struct hv_24x7_result results[]; /* [@num_results] */
+        struct hv_24x7_result results[1]; /* [@num_results] */
 } __packed;
 
 #endif