From 6dc2a774cb4fdb524b7eb0b8db74198a1b4815ea Mon Sep 17 00:00:00 2001 From: Sunil Muthuswamy Date: Tue, 23 Mar 2021 18:47:16 +0000 Subject: x86/Hyper-V: Support for free page reporting Linux has support for free page reporting now (36e66c554b5c) for virtualized environment. On Hyper-V when virtually backed VMs are configured, Hyper-V will advertise cold memory discard capability, when supported. This patch adds the support to hook into the free page reporting infrastructure and leverage the Hyper-V cold memory discard hint hypercall to report/free these pages back to the host. Signed-off-by: Sunil Muthuswamy Tested-by: Matheus Castello Reviewed-by: Michael Kelley Tested-by: Nathan Chancellor Link: https://lore.kernel.org/r/SN4PR2101MB0880121FA4E2FEC67F35C1DCC0649@SN4PR2101MB0880.namprd21.prod.outlook.com Signed-off-by: Wei Liu --- drivers/hv/Kconfig | 1 + drivers/hv/hv_balloon.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 90 insertions(+) (limited to 'drivers/hv') diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index 79e5356a737a..66c794d92391 100644 --- a/drivers/hv/Kconfig +++ b/drivers/hv/Kconfig @@ -23,6 +23,7 @@ config HYPERV_UTILS config HYPERV_BALLOON tristate "Microsoft Hyper-V Balloon driver" depends on HYPERV + select PAGE_REPORTING help Select this option to enable Hyper-V Balloon driver. diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 2f776d78e3c1..58af84e30144 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -563,6 +564,8 @@ struct hv_dynmem_device { * The negotiated version agreed by host. */ __u32 version; + + struct page_reporting_dev_info pr_dev_info; }; static struct hv_dynmem_device dm_device; @@ -1568,6 +1571,89 @@ static void balloon_onchannelcallback(void *context) } +/* Hyper-V only supports reporting 2MB pages or higher */ +#define HV_MIN_PAGE_REPORTING_ORDER 9 +#define HV_MIN_PAGE_REPORTING_LEN (HV_HYP_PAGE_SIZE << HV_MIN_PAGE_REPORTING_ORDER) +static int hv_free_page_report(struct page_reporting_dev_info *pr_dev_info, + struct scatterlist *sgl, unsigned int nents) +{ + unsigned long flags; + struct hv_memory_hint *hint; + int i; + u64 status; + struct scatterlist *sg; + + WARN_ON_ONCE(nents > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES); + WARN_ON_ONCE(sgl->length < HV_MIN_PAGE_REPORTING_LEN); + local_irq_save(flags); + hint = *(struct hv_memory_hint **)this_cpu_ptr(hyperv_pcpu_input_arg); + if (!hint) { + local_irq_restore(flags); + return -ENOSPC; + } + + hint->type = HV_EXT_MEMORY_HEAT_HINT_TYPE_COLD_DISCARD; + hint->reserved = 0; + for_each_sg(sgl, sg, nents, i) { + union hv_gpa_page_range *range; + + range = &hint->ranges[i]; + range->address_space = 0; + /* page reporting only reports 2MB pages or higher */ + range->page.largepage = 1; + range->page.additional_pages = + (sg->length / HV_MIN_PAGE_REPORTING_LEN) - 1; + range->page_size = HV_GPA_PAGE_RANGE_PAGE_SIZE_2MB; + range->base_large_pfn = + page_to_hvpfn(sg_page(sg)) >> HV_MIN_PAGE_REPORTING_ORDER; + } + + status = hv_do_rep_hypercall(HV_EXT_CALL_MEMORY_HEAT_HINT, nents, 0, + hint, NULL); + local_irq_restore(flags); + if ((status & HV_HYPERCALL_RESULT_MASK) != HV_STATUS_SUCCESS) { + pr_err("Cold memory discard hypercall failed with status %llx\n", + status); + return -EINVAL; + } + + return 0; +} + +static void enable_page_reporting(void) +{ + int ret; + + /* Essentially, validating 'PAGE_REPORTING_MIN_ORDER' is big enough. */ + if (pageblock_order < HV_MIN_PAGE_REPORTING_ORDER) { + pr_debug("Cold memory discard is only supported on 2MB pages and above\n"); + return; + } + + if (!hv_query_ext_cap(HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT)) { + pr_debug("Cold memory discard hint not supported by Hyper-V\n"); + return; + } + + BUILD_BUG_ON(PAGE_REPORTING_CAPACITY > HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES); + dm_device.pr_dev_info.report = hv_free_page_report; + ret = page_reporting_register(&dm_device.pr_dev_info); + if (ret < 0) { + dm_device.pr_dev_info.report = NULL; + pr_err("Failed to enable cold memory discard: %d\n", ret); + } else { + pr_info("Cold memory discard hint enabled\n"); + } +} + +static void disable_page_reporting(void) +{ + if (dm_device.pr_dev_info.report) { + page_reporting_unregister(&dm_device.pr_dev_info); + dm_device.pr_dev_info.report = NULL; + } +} + static int balloon_connect_vsp(struct hv_device *dev) { struct dm_version_request version_req; @@ -1713,6 +1799,7 @@ static int balloon_probe(struct hv_device *dev, if (ret != 0) return ret; + enable_page_reporting(); dm_device.state = DM_INITIALIZED; dm_device.thread = @@ -1727,6 +1814,7 @@ static int balloon_probe(struct hv_device *dev, probe_error: dm_device.state = DM_INIT_ERROR; dm_device.thread = NULL; + disable_page_reporting(); vmbus_close(dev->channel); #ifdef CONFIG_MEMORY_HOTPLUG unregister_memory_notifier(&hv_memory_nb); @@ -1749,6 +1837,7 @@ static int balloon_remove(struct hv_device *dev) cancel_work_sync(&dm->ha_wrk.wrk); kthread_stop(dm->thread); + disable_page_reporting(); vmbus_close(dev->channel); #ifdef CONFIG_MEMORY_HOTPLUG unregister_memory_notifier(&hv_memory_nb); -- cgit