On 3/3/26 16:23, Stanislav Kinsburskii wrote:
Deposit enough pages up front to avoid virtual processor creation failures
due to low memory. This also speeds up guest creation. A VP uses 25% more
pages in a partition with nested virtualization enabled, but the exact
number doesn't vary much, so deposit a fixed number of pages per VP that
works for nested virtualization.
Move page depositing from the hypercall wrapper to the virtual processor
creation code. The required number of pages is based on empirical data.
This logic fits better in the virtual processor creation code than in the
hypercall wrapper.
Also withdraw the deposited memory if virtual processor creation fails.
Signed-off-by: Stanislav Kinsburskii <[email protected]>
---
drivers/hv/hv_proc.c | 8 --------
drivers/hv/mshv_root_main.c | 11 ++++++++++-
2 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c
index 0f84a70def30..3d41f52efd9a 100644
--- a/drivers/hv/hv_proc.c
+++ b/drivers/hv/hv_proc.c
@@ -251,14 +251,6 @@ int hv_call_create_vp(int node, u64 partition_id, u32
vp_index, u32 flags)
unsigned long irq_flags;
int ret = 0;
- /* Root VPs don't seem to need pages deposited */
- if (partition_id != hv_current_partition_id) {
- /* The value 90 is empirically determined. It may change. */
- ret = hv_call_deposit_pages(node, partition_id, 90);
- if (ret)
- return ret;
- }
-
do {
local_irq_save(irq_flags);
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index fbfc50de332c..48c842b6938d 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -38,6 +38,7 @@
/* The deposit values below are empirical and may need to be adjusted. */
#define MSHV_PARTITION_DEPOSIT_PAGES (SZ_512K >> PAGE_SHIFT)
#define MSHV_PARTITION_DEPOSIT_PAGES_NESTED (20 * SZ_1M >> PAGE_SHIFT)
+#define MSHV_VP_DEPOSIT_PAGES (1 * SZ_1M >> PAGE_SHIFT)
This seems to assume that each vp will use up total of 1M, and I don't
think that is the case. My understanding, hyp will reuse remaining chunks.
IOW, 6M maybe enought for 8 vcpus.
MODULE_AUTHOR("Microsoft");
MODULE_LICENSE("GPL");
@@ -1077,10 +1078,15 @@ mshv_partition_ioctl_create_vp(struct mshv_partition
*partition,
if (partition->pt_vp_array[args.vp_index])
return -EEXIST;
+ ret = hv_call_deposit_pages(NUMA_NO_NODE, partition->pt_id,
+ MSHV_VP_DEPOSIT_PAGES);
+ if (ret)
+ return ret;
+
ret = hv_call_create_vp(NUMA_NO_NODE, partition->pt_id, args.vp_index,
0 /* Only valid for root partition VPs */);
if (ret)
- return ret;
+ goto withdraw_mem;
ret = hv_map_vp_state_page(partition->pt_id, args.vp_index,
HV_VP_STATE_PAGE_INTERCEPT_MESSAGE,
@@ -1177,6 +1183,9 @@ mshv_partition_ioctl_create_vp(struct mshv_partition
*partition,
intercept_msg_page, input_vtl_zero);
destroy_vp:
hv_call_delete_vp(partition->pt_id, args.vp_index);
+withdraw_mem:
+ hv_call_withdraw_memory(MSHV_VP_DEPOSIT_PAGES, NUMA_NO_NODE,
+ partition->pt_id);
out:
trace_mshv_create_vp(partition->pt_id, args.vp_index, ret);
return ret;
