x86: hap dirty vram tracking

Currently HAP systems suffer a significant performance loss when a vnc
client is connect or the sdl interface is used, because HAP is lacking
an implementation of track_dirty_vram.
As a consequence qemu always tries to update the whole screen because
it does not know which areas of the screen have been updated by the
guest.

This patch implements track_dirty_vram for HAP enabling the logdirty
mechanism only in a specific gfn range and adding a
paging_log_dirty_range function that returns the log dirty bitmap in a
requested range.

Paging_log_dirty_range is different from paging_log_dirty_op because
operates on a range and also because it does not pause the domain. In
order not to lose any update I moved clean_dirty_bitmap at the
beginning of the function before evaluating the logdirty bitmap.
The bitmap is still safe because it is protected by the logdirty lock.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/xen/include/asm-x86/paging.h b/xen/include/asm-x86/paging.h
index 11e96ee957..f26c5e83a7 100644
--- a/xen/include/asm-x86/paging.h
+++ b/xen/include/asm-x86/paging.h
@@ -139,6 +139,12 @@ int paging_alloc_log_dirty_bitmap(struct domain *d);
 /* free log dirty bitmap resource */
 void paging_free_log_dirty_bitmap(struct domain *d);
 
+/* get the dirty bitmap for a specific range of pfns */
+int paging_log_dirty_range(struct domain *d,
+                           unsigned long begin_pfn,
+                           unsigned long nr,
+                           XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
+
 /* enable log dirty */
 int paging_log_dirty_enable(struct domain *d);
 
@@ -176,6 +182,15 @@ void paging_mark_dirty(struct domain *d, unsigned long guest_mfn);
 #define L4_LOGDIRTY_IDX(pfn) 0
 #endif
 
+/* VRAM dirty tracking support */
+struct sh_dirty_vram {
+    unsigned long begin_pfn;
+    unsigned long end_pfn;
+    paddr_t *sl1ma;
+    uint8_t *dirty_bitmap;
+    s_time_t last_dirty;
+};
+
 /*****************************************************************************
  * Entry points into the paging-assistance code */