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Re: [Qemu-devel] [PATCH v4 1/6] vhost: Move log_dirty check
From: |
Igor Mammedov |
Subject: |
Re: [Qemu-devel] [PATCH v4 1/6] vhost: Move log_dirty check |
Date: |
Thu, 14 Dec 2017 15:30:28 +0100 |
On Wed, 13 Dec 2017 18:08:02 +0000
"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Move the log_dirty check into vhost_section.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
> hw/virtio/trace-events | 3 +++
> hw/virtio/vhost.c | 20 +++++++++++++-------
> 2 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 775461ae98..4a493bcd46 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -1,5 +1,8 @@
> # See docs/devel/tracing.txt for syntax documentation.
>
> +# hw/virtio/vhost.c
> +vhost_section(const char *name, int r) "%s:%d"
> +
> # hw/virtio/virtio.c
> virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned
> out_num) "elem %p size %zd in_num %u out_num %u"
> virtqueue_fill(void *vq, const void *elem, unsigned int len, unsigned int
> idx) "vq %p elem %p len %u idx %u"
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index e4290ce93d..e923219e63 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -27,6 +27,7 @@
> #include "hw/virtio/virtio-access.h"
> #include "migration/blocker.h"
> #include "sysemu/dma.h"
> +#include "trace.h"
>
> /* enabled until disconnected backend stabilizes */
> #define _VHOST_DEBUG 1
> @@ -567,18 +568,12 @@ static void vhost_set_memory(MemoryListener *listener,
> memory_listener);
> hwaddr start_addr = section->offset_within_address_space;
> ram_addr_t size = int128_get64(section->size);
> - bool log_dirty =
> - memory_region_get_dirty_log_mask(section->mr) & ~(1 <<
> DIRTY_MEMORY_MIGRATION);
> int s = offsetof(struct vhost_memory, regions) +
> (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
> void *ram;
>
> dev->mem = g_realloc(dev->mem, s);
>
> - if (log_dirty) {
> - add = false;
> - }
> -
> assert(size);
>
> /* Optimize no-change case. At least cirrus_vga does this a lot at this
> time. */
> @@ -611,8 +606,19 @@ static void vhost_set_memory(MemoryListener *listener,
>
> static bool vhost_section(MemoryRegionSection *section)
> {
> - return memory_region_is_ram(section->mr) &&
> + bool result;
> + bool log_dirty = memory_region_get_dirty_log_mask(section->mr) &
> + ~(1 << DIRTY_MEMORY_MIGRATION);
> + result = memory_region_is_ram(section->mr) &&
> !memory_region_is_rom(section->mr);
> +
> + /* Vhost doesn't handle any block which is doing dirty-tracking other
> + * than migration; this typically fires on VGA areas.
> + */
> + result &= !log_dirty;
before patch even if log_dirty, vhost_set_memory will still proceed
and may remove dirty section from memmap and set memory_changed = true
but with this patch it will just ignore such section,
I'm not sure it's right (it might be right with new approach add/nop
but then this patch should go after new code in place and old one
if gone).
> +
> + trace_vhost_section(section->mr->name, result);
> + return result;
> }
>
> static void vhost_begin(MemoryListener *listener)