linux-kernel - [RFC PATCH 2/3] mshv: Account pages deposited to hypervisor

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Message-ID: 
 <176928014080.26405.17823443762395754699.stgit@skinsburskii-cloud-desktop.internal.cloudapp.net>
Date: Sat, 24 Jan 2026 18:42:20 +0000
From: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
To: pasha.tatashin@...een.com, rppt@...nel.org, pratyush@...nel.org,
 kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
 decui@...rosoft.com, longli@...rosoft.com
Cc: linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 2/3] mshv: Account pages deposited to hypervisor

This is a preparatory change for blocking kexec is there are any pages
deposited, as this information is lost after kexec and the pages aren't
accessible by kernel.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
---
 drivers/hv/hv_proc.c           |    4 ++++
 drivers/hv/mshv_root.h         |    1 +
 drivers/hv/mshv_root_hv_call.c |    2 ++
 3 files changed, 7 insertions(+)

diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
index 89870c1b0087..39bbbedb0340 100644
--- a/drivers/hv/hv_proc.c
+++ b/drivers/hv/hv_proc.c
@@ -15,6 +15,8 @@
  */
 #define HV_DEPOSIT_MAX (HV_HYP_PAGE_SIZE / sizeof(u64) - 1)
 
+atomic_t hv_pages_deposited;
+
 /* Deposits exact number of pages. Must be called with interrupts enabled.  */
 int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
 {
@@ -93,6 +95,8 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages)
 		goto err_free_allocations;
 	}
 
+	atomic_add(page_count, &hv_pages_deposited);
+
 	ret = 0;
 	goto free_buf;
 
diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 3c1d88b36741..c792afce0839 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -319,6 +319,7 @@ int hv_call_get_partition_property_ex(u64 partition_id, u64 property_code, u64 a
 extern struct mshv_root mshv_root;
 extern enum hv_scheduler_type hv_scheduler_type;
 extern u8 * __percpu *hv_synic_eventring_tail;
+extern atomic_t hv_pages_deposited;
 
 struct mshv_mem_region *mshv_region_create(u64 guest_pfn, u64 nr_pages,
 					   u64 uaddr, u32 flags);
diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c
index 06f2bac8039d..4203af5190ee 100644
--- a/drivers/hv/mshv_root_hv_call.c
+++ b/drivers/hv/mshv_root_hv_call.c
@@ -73,6 +73,8 @@ int hv_call_withdraw_memory(u64 count, int node, u64 partition_id)
 		for (i = 0; i < completed; i++)
 			__free_page(pfn_to_page(output_page->gpa_page_list[i]));
 
+		atomic_sub(completed, &hv_pages_deposited);
+
 		if (!hv_result_success(status)) {
 			if (hv_result(status) == HV_STATUS_NO_RESOURCES)
 				status = HV_STATUS_SUCCESS;