From: Alexander Atanasov <alexander.atanasov@xxxxxxxxxxxxx> Sent: Wednesday, July 6, 2022 11:15 AM > > Allow the guest to know how much it is ballooned by the host. > It is useful when debugging out of memory conditions. > > When host gets back memory from the guest it is accounted > as used memory in the guest but the guest have no way to know > how much it is actually ballooned. > > Expose current state, flags and max possible memory to the guest. > While at it - fix a 10+ years old typo. > > Signed-off-by: Alexander Atanasov <alexander.atanasov@xxxxxxxxxxxxx> > --- > drivers/hv/hv_balloon.c | 126 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 125 insertions(+), 1 deletion(-) > > V1->V2: > - Fix C&P errors - you got me :) Did you see my code comments on v1 of your patch (in addition to my broader comment about debugfs vs. tracing) ? I didn't see a response from you, and my code suggestions are not incorporated into this v2, so I wondered if you disagreed with my suggestions, or just missed them. Michael > > Note - no attempt to handle guest vs host page size difference > is made - see ballooning_enabled. > Basicly if balloon page size != guest page size balloon is off. > > diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c > index 91e8a72eee14..91dfde06c6fb 100644 > --- a/drivers/hv/hv_balloon.c > +++ b/drivers/hv/hv_balloon.c > @@ -11,6 +11,7 @@ > #include <linux/kernel.h> > #include <linux/jiffies.h> > #include <linux/mman.h> > +#include <linux/debugfs.h> > #include <linux/delay.h> > #include <linux/init.h> > #include <linux/module.h> > @@ -248,7 +249,7 @@ struct dm_capabilities_resp_msg { > * num_committed: Committed memory in pages. > * page_file_size: The accumulated size of all page files > * in the system in pages. > - * zero_free: The nunber of zero and free pages. > + * zero_free: The number of zero and free pages. > * page_file_writes: The writes to the page file in pages. > * io_diff: An indicator of file cache efficiency or page file activity, > * calculated as File Cache Page Fault Count - Page Read Count. > @@ -567,6 +568,13 @@ struct hv_dynmem_device { > __u32 version; > > struct page_reporting_dev_info pr_dev_info; > + > +#ifdef CONFIG_DEBUG_FS > + /* > + * Maximum number of pages that can be hot_add-ed > + */ > + __u64 max_dynamic_page_count; > +#endif > }; > > static struct hv_dynmem_device dm_device; > @@ -1078,6 +1086,9 @@ static void process_info(struct hv_dynmem_device *dm, > struct dm_info_msg *msg) > > pr_info("Max. dynamic memory size: %llu MB\n", > (*max_page_count) >> (20 - HV_HYP_PAGE_SHIFT)); > +#ifdef CONFIG_DEBUG_FS > + dm->max_dynamic_page_count = *max_page_count; > +#endif > } > > break; > @@ -1807,6 +1818,115 @@ static int balloon_connect_vsp(struct hv_device *dev) > return ret; > } > > +/* > + * DEBUGFS Interface > + */ > +#ifdef CONFIG_DEBUG_FS > + > +/** > + * hv_balloon_debug_show - shows statistics of balloon operations. > + * @f: pointer to the &struct seq_file. > + * @offset: ignored. > + * > + * Provides the statistics that can be accessed in hv-balloon in the debugfs. > + * > + * Return: zero on success or an error code. > + */ > +static int hv_balloon_debug_show(struct seq_file *f, void *offset) > +{ > + struct hv_dynmem_device *dm = f->private; > + unsigned long num_pages_committed; > + char *sname; > + > + seq_printf(f, "%-22s: %u.%u\n", "host_version", > + DYNMEM_MAJOR_VERSION(dm->version), > + DYNMEM_MINOR_VERSION(dm->version)); > + > + seq_printf(f, "%-22s:", "capabilities"); > + if (ballooning_enabled()) > + seq_puts(f, " enabled"); > + > + if (hot_add_enabled()) > + seq_puts(f, " hot_add"); > + > + seq_puts(f, "\n"); > + > + seq_printf(f, "%-22s: %u", "state", dm->state); > + switch (dm->state) { > + case DM_INITIALIZING: > + sname = "Initializing"; > + break; > + case DM_INITIALIZED: > + sname = "Initialized"; > + break; > + case DM_BALLOON_UP: > + sname = "Balloon Up"; > + break; > + case DM_BALLOON_DOWN: > + sname = "Balloon Down"; > + break; > + case DM_HOT_ADD: > + sname = "Hot Add"; > + break; > + case DM_INIT_ERROR: > + sname = "Error"; > + break; > + default: > + sname = "Unknown"; > + } > + seq_printf(f, " (%s)\n", sname); > + > + /* HV Page Size */ > + seq_printf(f, "%-22s: %ld\n", "page_size", HV_HYP_PAGE_SIZE); > + > + /* Pages added with hot_add */ > + seq_printf(f, "%-22s: %u\n", "pages_added", dm->num_pages_added); > + > + /* pages that are "onlined"/used from pages_added */ > + seq_printf(f, "%-22s: %u\n", "pages_onlined", dm->num_pages_onlined); > + > + /* pages we have given back to host */ > + seq_printf(f, "%-22s: %u\n", "pages_ballooned", dm->num_pages_ballooned); > + > + num_pages_committed = vm_memory_committed(); > + num_pages_committed += dm->num_pages_ballooned + > + (dm->num_pages_added > dm->num_pages_onlined ? > + dm->num_pages_added - dm->num_pages_onlined : 0) + > + compute_balloon_floor(); > + seq_printf(f, "%-22s: %lu\n", "total_pages_commited", > + num_pages_committed); > + > + seq_printf(f, "%-22s: %llu\n", "max_dynamic_page_count", > + dm->max_dynamic_page_count); > + > + return 0; > +} > + > +DEFINE_SHOW_ATTRIBUTE(hv_balloon_debug); > + > +static void hv_balloon_debugfs_init(struct hv_dynmem_device *b) > +{ > + debugfs_create_file("hv-balloon", 0444, NULL, b, > + &hv_balloon_debug_fops); > +} > + > +static void hv_balloon_debugfs_exit(struct hv_dynmem_device *b) > +{ > + debugfs_remove(debugfs_lookup("hv-balloon", NULL)); > +} > + > +#else > + > +static inline void hv_balloon_debugfs_init(struct hv_dynmem_device *b) > +{ > +} > + > +static inline void hv_balloon_debugfs_exit(struct hv_dynmem_device *b) > +{ > +} > + > +#endif /* CONFIG_DEBUG_FS */ > + > static int balloon_probe(struct hv_device *dev, > const struct hv_vmbus_device_id *dev_id) > { > @@ -1854,6 +1974,8 @@ static int balloon_probe(struct hv_device *dev, > goto probe_error; > } > > + hv_balloon_debugfs_init(&dm_device); > + > return 0; > > probe_error: > @@ -1879,6 +2001,8 @@ static int balloon_remove(struct hv_device *dev) > if (dm->num_pages_ballooned != 0) > pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned); > > + hv_balloon_debugfs_exit(dm); > + > cancel_work_sync(&dm->balloon_wrk.wrk); > cancel_work_sync(&dm->ha_wrk.wrk); > > -- > 2.25.1