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[PATCH v3 2/2] vhost: Only align sections for vhost-user
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PATCH v3 2/2] vhost: Only align sections for vhost-user |
Date: |
Thu, 16 Jan 2020 20:24:14 +0000 |
From: "Dr. David Alan Gilbert" <address@hidden>
I added hugepage alignment code in c1ece84e7c9 to deal with
vhost-user + postcopy which needs aligned pages when using userfault.
However, on x86 the lower 2MB of address space tends to be shotgun'd
with small fragments around the 512-640k range - e.g. video RAM, and
with HyperV synic pages tend to sit around there - again splitting
it up. The alignment code complains with a 'Section rounded to ...'
error and gives up.
Since vhost-user already filters out devices without an fd
(see vhost-user.c vhost_user_mem_section_filter) it shouldn't be
affected by those overlaps.
Turn the alignment off on vhost-kernel so that it doesn't try
and align, and thus won't hit the rounding issues.
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
hw/virtio/vhost.c | 34 ++++++++++++++++++----------------
1 file changed, 18 insertions(+), 16 deletions(-)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 774d87d98e..25fd469179 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -547,26 +547,28 @@ static void vhost_region_add_section(struct vhost_dev
*dev,
uintptr_t mrs_host = (uintptr_t)memory_region_get_ram_ptr(section->mr) +
section->offset_within_region;
RAMBlock *mrs_rb = section->mr->ram_block;
- size_t mrs_page = qemu_ram_pagesize(mrs_rb);
trace_vhost_region_add_section(section->mr->name, mrs_gpa, mrs_size,
mrs_host);
- /* Round the section to it's page size */
- /* First align the start down to a page boundary */
- uint64_t alignage = mrs_host & (mrs_page - 1);
- if (alignage) {
- mrs_host -= alignage;
- mrs_size += alignage;
- mrs_gpa -= alignage;
- }
- /* Now align the size up to a page boundary */
- alignage = mrs_size & (mrs_page - 1);
- if (alignage) {
- mrs_size += mrs_page - alignage;
- }
- trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa,
mrs_size,
- mrs_host);
+ if (dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER) {
+ /* Round the section to it's page size */
+ /* First align the start down to a page boundary */
+ size_t mrs_page = qemu_ram_pagesize(mrs_rb);
+ uint64_t alignage = mrs_host & (mrs_page - 1);
+ if (alignage) {
+ mrs_host -= alignage;
+ mrs_size += alignage;
+ mrs_gpa -= alignage;
+ }
+ /* Now align the size up to a page boundary */
+ alignage = mrs_size & (mrs_page - 1);
+ if (alignage) {
+ mrs_size += mrs_page - alignage;
+ }
+ trace_vhost_region_add_section_aligned(section->mr->name, mrs_gpa,
mrs_size,
+ mrs_host);
+ }
if (dev->n_tmp_sections) {
/* Since we already have at least one section, lets see if
--
2.24.1
[PATCH v3 1/2] vhost: Add names to section rounded warning, Dr. David Alan Gilbert (git), 2020/01/16
Re: [PATCH v3 0/2] Fix hyperv synic on vhost, no-reply, 2020/01/16