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authorSunil Muthuswamy <sunilmut@microsoft.com>2021-03-23 18:47:16 +0000
committerWei Liu <wei.liu@kernel.org>2021-03-24 11:35:24 +0000
commit6dc2a774cb4fdb524b7eb0b8db74198a1b4815ea (patch)
tree537cf3fba82d5d7e438f930a428b564c8d6b6e8e /drivers/hv
parent1b60280834683dddf4975bbf9662a74f123ba770 (diff)
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 <sunilmut@microsoft.com> Tested-by: Matheus Castello <matheus@castello.eng.br> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/SN4PR2101MB0880121FA4E2FEC67F35C1DCC0649@SN4PR2101MB0880.namprd21.prod.outlook.com Signed-off-by: Wei Liu <wei.liu@kernel.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/Kconfig1
-rw-r--r--drivers/hv/hv_balloon.c89
2 files changed, 90 insertions, 0 deletions
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 <linux/memory.h>
#include <linux/notifier.h>
#include <linux/percpu_counter.h>
+#include <linux/page_reporting.h>
#include <linux/hyperv.h>
#include <asm/hyperv-tlfs.h>
@@ -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);