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, 5 insertions, 0 deletions

diff --git a/xen/include/asm-x86/hap.h b/xen/include/asm-x86/hap.h
index 60a2ad4ed0..3f3cf3f22e 100644
--- a/xen/include/asm-x86/hap.h
+++ b/xen/include/asm-x86/hap.h
@@ -91,6 +91,11 @@ int   hap_enable(struct domain *d, u32 mode);
 void  hap_final_teardown(struct domain *d);
 void  hap_teardown(struct domain *d);
 void  hap_vcpu_init(struct vcpu *v);
+void  hap_logdirty_init(struct domain *d);
+int   hap_track_dirty_vram(struct domain *d,
+                           unsigned long begin_pfn,
+                           unsigned long nr,
+                           XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
 
 extern struct paging_mode hap_paging_real_mode;
 extern struct paging_mode hap_paging_protected_mode;