[PATCH 07/19] drivers/hv: withdraw memory hypercall

From: Nuno Das Neves
Date: Fri May 28 2021 - 18:44:05 EST


Withdraw the memory from a finalized partition and free the pages.
The partition is now cleaned up correctly when the fd is released.

Co-developed-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
---
drivers/hv/hv_call.c | 53 +++++++++++++++++++++++++++++++
drivers/hv/mshv.h | 6 ++++
drivers/hv/mshv_main.c | 5 +--
include/asm-generic/hyperv-tlfs.h | 11 +++++++
4 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/hv_call.c b/drivers/hv/hv_call.c
index 7d85f1bd959a..73cc1fb59e60 100644
--- a/drivers/hv/hv_call.c
+++ b/drivers/hv/hv_call.c
@@ -14,6 +14,59 @@

#include "mshv.h"

+int hv_call_withdraw_memory(u64 count, int node, u64 partition_id)
+{
+ struct hv_withdraw_memory_in *input_page;
+ struct hv_withdraw_memory_out *output_page;
+ struct page *page;
+ u16 completed;
+ unsigned long remaining = count;
+ u64 status;
+ int i;
+ unsigned long flags;
+
+ page = alloc_page(GFP_KERNEL);
+ if (!page)
+ return -ENOMEM;
+ output_page = page_address(page);
+
+ while (remaining) {
+ local_irq_save(flags);
+
+ input_page = (struct hv_withdraw_memory_in *)(*this_cpu_ptr(
+ hyperv_pcpu_input_arg));
+
+ input_page->partition_id = partition_id;
+ input_page->proximity_domain_info.as_uint64 = 0;
+ status = hv_do_rep_hypercall(
+ HVCALL_WITHDRAW_MEMORY,
+ min(remaining, HV_WITHDRAW_BATCH_SIZE), 0, input_page,
+ output_page);
+
+ local_irq_restore(flags);
+
+ completed = hv_repcomp(status);
+
+ for (i = 0; i < completed; i++)
+ __free_page(pfn_to_page(output_page->gpa_page_list[i]));
+
+ if (!hv_result_success(status)) {
+ if (hv_result(status) == HV_STATUS_NO_RESOURCES)
+ status = HV_STATUS_SUCCESS;
+ else
+ pr_err("%s: %s\n", __func__,
+ hv_status_to_string(status));
+ break;
+ }
+
+ remaining -= completed;
+ }
+ free_page((unsigned long)output_page);
+
+ return hv_status_to_errno(status);
+}
+
+
int hv_call_create_partition(
u64 flags,
struct hv_partition_creation_properties creation_properties,
diff --git a/drivers/hv/mshv.h b/drivers/hv/mshv.h
index 46121bd30592..cf48ec5840b7 100644
--- a/drivers/hv/mshv.h
+++ b/drivers/hv/mshv.h
@@ -11,12 +11,18 @@
#ifndef _MSHV_H_
#define _MSHV_H_

+#include<asm/hyperv-tlfs.h>
+
/* Determined empirically */
#define HV_INIT_PARTITION_DEPOSIT_PAGES 208

+#define HV_WITHDRAW_BATCH_SIZE (HV_HYP_PAGE_SIZE / sizeof(u64))
+
/*
* Hyper-V hypercalls
*/
+
+int hv_call_withdraw_memory(u64 count, int node, u64 partition_id);
int hv_call_create_partition(
u64 flags,
struct hv_partition_creation_properties creation_properties,
diff --git a/drivers/hv/mshv_main.c b/drivers/hv/mshv_main.c
index c32618357da8..41afaa86de73 100644
--- a/drivers/hv/mshv_main.c
+++ b/drivers/hv/mshv_main.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/anon_inodes.h>
+#include <linux/mm.h>
#include <linux/mshv.h>
#include <asm/mshyperv.h>

@@ -52,7 +53,6 @@ static struct miscdevice mshv_dev = {
.mode = 600,
};

-
static long
mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
{
@@ -89,7 +89,8 @@ destroy_partition(struct mshv_partition *partition)

/* Deallocates and unmaps everything including vcpus, GPA mappings etc */
hv_call_finalize_partition(partition->id);
- /* TODO: Withdraw and free all pages we deposited */
+ /* Withdraw and free all pages we deposited */
+ hv_call_withdraw_memory(U64_MAX, NUMA_NO_NODE, partition->id);

hv_call_delete_partition(partition->id);

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 49099b7e0f71..2e1573978569 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -149,6 +149,7 @@ struct ms_hyperv_tsc_page {
#define HVCALL_DELETE_PARTITION 0x0043
#define HVCALL_GET_PARTITION_ID 0x0046
#define HVCALL_DEPOSIT_MEMORY 0x0048
+#define HVCALL_WITHDRAW_MEMORY 0x0049
#define HVCALL_CREATE_VP 0x004e
#define HVCALL_GET_VP_REGISTERS 0x0050
#define HVCALL_SET_VP_REGISTERS 0x0051
@@ -515,6 +516,16 @@ union hv_proximity_domain_info {
u64 as_uint64;
} __packed;

+struct hv_withdraw_memory_in {
+ u64 partition_id;
+ union hv_proximity_domain_info proximity_domain_info;
+} __packed;
+
+struct hv_withdraw_memory_out {
+ /* Hack - compiler doesn't like empty array size in struct with no other members */
+ u64 gpa_page_list[0];
+} __packed;
+
struct hv_lp_startup_status {
u64 hv_status;
u64 substatus1;
--
2.25.1