[Qemu-devel] [5793] vga optimization (Glauber Costa)

[Anthony Liguori]

Revision: 5793
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5793
Author:   aliguori
Date:     2008-11-24 20:21:41 +0000 (Mon, 24 Nov 2008)

Log Message:
-----------
vga optimization (Glauber Costa)

Hypervisors like KVM perform badly while doing mmio on
a loop, because it'll generate an exit on each access.
This is the case with VGA, which results in very bad
performance.

In this patch, we map the linear frame buffer as RAM,
make sure it has dirty region tracking enabled, and then
just let the region to be written.

Cleanups suggestions by:
  Stefano Stabellini <address@hidden>

Signed-off-by: Glauber Costa <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>

Modified Paths:
--------------
    trunk/cpu-all.h
    trunk/exec.c
    trunk/hw/cirrus_vga.c
    trunk/hw/vga.c
    trunk/hw/vga_int.h

Modified: trunk/cpu-all.h
===================================================================
--- trunk/cpu-all.h     2008-11-24 19:36:26 UTC (rev 5792)
+++ trunk/cpu-all.h     2008-11-24 20:21:41 UTC (rev 5793)
@@ -948,6 +948,8 @@
 
 int cpu_physical_memory_get_dirty_tracking(void);
 
+void cpu_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, 
target_phys_addr_t end_addr);
+
 void dump_exec_info(FILE *f,
                     int (*cpu_fprintf)(FILE *f, const char *fmt, ...));
 

Modified: trunk/exec.c
===================================================================
--- trunk/exec.c        2008-11-24 19:36:26 UTC (rev 5792)
+++ trunk/exec.c        2008-11-24 20:21:41 UTC (rev 5793)
@@ -1887,6 +1887,12 @@
     return in_migration;
 }
 
+void cpu_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, 
target_phys_addr_t end_addr)
+{
+    if (kvm_enabled())
+        kvm_physical_sync_dirty_bitmap(start_addr, end_addr);
+}
+
 static inline void tlb_update_dirty(CPUTLBEntry *tlb_entry)
 {
     ram_addr_t ram_addr;

Modified: trunk/hw/cirrus_vga.c
===================================================================
--- trunk/hw/cirrus_vga.c       2008-11-24 19:36:26 UTC (rev 5792)
+++ trunk/hw/cirrus_vga.c       2008-11-24 20:21:41 UTC (rev 5793)
@@ -31,6 +31,7 @@
 #include "pci.h"
 #include "console.h"
 #include "vga_int.h"
+#include "kvm.h"
 
 /*
  * TODO:
@@ -1228,6 +1229,12 @@
     }
 
     if (limit > 0) {
+        /* Thinking about changing bank base? First, drop the dirty bitmap 
information
+         * on the current location, otherwise we lose this pointer forever */
+        if (s->lfb_vram_mapped) {
+            target_phys_addr_t base_addr = isa_mem_base + 0xa0000 + bank_index 
* 0x8000;
+            cpu_physical_sync_dirty_bitmap(base_addr, base_addr + 0x8000);
+        }
        s->cirrus_bank_base[bank_index] = offset;
        s->cirrus_bank_limit[bank_index] = limit;
     } else {
@@ -1356,6 +1363,7 @@
        s->hw_cursor_y = (reg_value << 3) | (reg_index >> 5);
        break;
     case 0x07:                 // Extended Sequencer Mode
+    cirrus_update_memory_access(s);
     case 0x08:                 // EEPROM Control
     case 0x09:                 // Scratch Register 0
     case 0x0a:                 // Scratch Register 1
@@ -1528,6 +1536,7 @@
        s->gr[reg_index] = reg_value;
        cirrus_update_bank_ptr(s, 0);
        cirrus_update_bank_ptr(s, 1);
+        cirrus_update_memory_access(s);
         break;
     case 0x0B:
        s->gr[reg_index] = reg_value;
@@ -2618,6 +2627,52 @@
     cirrus_linear_bitblt_writel,
 };
 
+static void map_linear_vram(CirrusVGAState *s)
+{
+
+    if (!s->map_addr && s->lfb_addr && s->lfb_end) {
+        s->map_addr = s->lfb_addr;
+        s->map_end = s->lfb_end;
+        cpu_register_physical_memory(s->map_addr, s->map_end - s->map_addr, 
s->vram_offset);
+        vga_dirty_log_start((VGAState *)s);
+    }
+
+    if (!s->map_addr)
+        return;
+
+    s->lfb_vram_mapped = 0;
+
+    if (!(s->cirrus_srcptr != s->cirrus_srcptr_end)
+        && !((s->sr[0x07] & 0x01) == 0)
+        && !((s->gr[0x0B] & 0x14) == 0x14)
+        && !(s->gr[0x0B] & 0x02)) {
+
+        cpu_register_physical_memory(isa_mem_base + 0xa0000, 0x8000,
+                                    (s->vram_offset + s->cirrus_bank_base[0]) 
| IO_MEM_RAM);
+        cpu_register_physical_memory(isa_mem_base + 0xa8000, 0x8000,
+                                    (s->vram_offset + s->cirrus_bank_base[1]) 
| IO_MEM_RAM);
+
+        s->lfb_vram_mapped = 1;
+        vga_dirty_log_start((VGAState *)s);
+    }
+    else {
+        cpu_register_physical_memory(isa_mem_base + 0xa0000, 0x8000, 
s->vga_io_memory);
+        cpu_register_physical_memory(isa_mem_base + 0xa8000, 0x8000, 
s->vga_io_memory);
+    }
+
+}
+
+static void unmap_linear_vram(CirrusVGAState *s)
+{
+    if (s->map_addr && s->lfb_addr && s->lfb_end) {
+        vga_dirty_log_stop((VGAState *)s);
+        s->map_addr = s->map_end = 0;
+    }
+
+    cpu_register_physical_memory(isa_mem_base + 0xa0000, 0x20000,
+                                 s->vga_io_memory);
+}
+
 /* Compute the memory access functions */
 static void cirrus_update_memory_access(CirrusVGAState *s)
 {
@@ -2636,11 +2691,13 @@
 
        mode = s->gr[0x05] & 0x7;
        if (mode < 4 || mode > 5 || ((s->gr[0x0B] & 0x4) == 0)) {
+            map_linear_vram(s);
             s->cirrus_linear_write[0] = cirrus_linear_mem_writeb;
             s->cirrus_linear_write[1] = cirrus_linear_mem_writew;
             s->cirrus_linear_write[2] = cirrus_linear_mem_writel;
         } else {
         generic_io:
+            unmap_linear_vram(s);
             s->cirrus_linear_write[0] = cirrus_linear_writeb;
             s->cirrus_linear_write[1] = cirrus_linear_writew;
             s->cirrus_linear_write[2] = cirrus_linear_writel;
@@ -3102,6 +3159,7 @@
     qemu_get_be32s(f, &s->hw_cursor_x);
     qemu_get_be32s(f, &s->hw_cursor_y);
 
+    cirrus_update_memory_access(s);
     /* force refresh */
     s->graphic_mode = -1;
     cirrus_update_bank_ptr(s, 0);
@@ -3261,6 +3319,13 @@
                                 s->cirrus_linear_io_addr);
     cpu_register_physical_memory(addr + 0x1000000, 0x400000,
                                 s->cirrus_linear_bitblt_io_addr);
+
+    s->map_addr = s->map_end = 0;
+    s->lfb_addr = addr & TARGET_PAGE_MASK;
+    s->lfb_end = ((addr + VGA_RAM_SIZE) + TARGET_PAGE_SIZE - 1) & 
TARGET_PAGE_MASK;
+    /* account for overflow */
+    if (s->lfb_end < addr + VGA_RAM_SIZE)
+        s->lfb_end = addr + VGA_RAM_SIZE;
 }
 
 static void cirrus_pci_mmio_map(PCIDevice *d, int region_num,

Modified: trunk/hw/vga.c
===================================================================
--- trunk/hw/vga.c      2008-11-24 19:36:26 UTC (rev 5792)
+++ trunk/hw/vga.c      2008-11-24 20:21:41 UTC (rev 5793)
@@ -28,6 +28,7 @@
 #include "vga_int.h"
 #include "pixel_ops.h"
 #include "qemu-timer.h"
+#include "kvm.h"
 
 //#define DEBUG_VGA
 //#define DEBUG_VGA_MEM
@@ -1243,6 +1244,8 @@
     vga_draw_glyph8_func *vga_draw_glyph8;
     vga_draw_glyph9_func *vga_draw_glyph9;
 
+    vga_dirty_log_stop(s);
+
     full_update |= update_palette16(s);
     palette = s->last_palette;
 
@@ -1556,6 +1559,18 @@
     }
 }
 
+static void vga_sync_dirty_bitmap(VGAState *s)
+{
+    if (s->map_addr)
+        cpu_physical_sync_dirty_bitmap(s->map_addr, s->map_end);
+
+    if (s->lfb_vram_mapped) {
+        cpu_physical_sync_dirty_bitmap(isa_mem_base + 0xa0000, 0xa8000);
+        cpu_physical_sync_dirty_bitmap(isa_mem_base + 0xa8000, 0xb0000);
+    }
+    vga_dirty_log_start(s);
+}
+
 /*
  * graphic modes
  */
@@ -1570,6 +1585,9 @@
 
     full_update |= update_basic_params(s);
 
+    if (!full_update)
+        vga_sync_dirty_bitmap(s);
+
     s->get_resolution(s, &width, &height);
     disp_width = width;
 
@@ -1743,6 +1761,8 @@
         return;
     if (s->last_scr_width <= 0 || s->last_scr_height <= 0)
         return;
+    vga_dirty_log_stop(s);
+
     if (ds_get_bits_per_pixel(s->ds) == 8)
         val = s->rgb_to_pixel(0, 0, 0);
     else
@@ -2092,6 +2112,28 @@
     VGAState vga_state;
 } PCIVGAState;
 
+void vga_dirty_log_start(VGAState *s)
+{
+    if (kvm_enabled() && s->map_addr)
+        kvm_log_start(s->map_addr, s->map_end - s->map_addr);
+
+    if (kvm_enabled() && s->lfb_vram_mapped) {
+        kvm_log_start(isa_mem_base + 0xa0000, 0x8000);
+        kvm_log_start(isa_mem_base + 0xa8000, 0x8000);
+    }
+}
+
+void vga_dirty_log_stop(VGAState *s)
+{
+    if (kvm_enabled() && s->map_addr)
+        kvm_log_stop(s->map_addr, s->map_end - s->map_addr);
+
+    if (kvm_enabled() && s->lfb_vram_mapped) {
+        kvm_log_stop(isa_mem_base + 0xa0000, 0x8000);
+        kvm_log_stop(isa_mem_base + 0xa8000, 0x8000);
+    }
+}
+
 static void vga_map(PCIDevice *pci_dev, int region_num,
                     uint32_t addr, uint32_t size, int type)
 {
@@ -2102,6 +2144,11 @@
     } else {
         cpu_register_physical_memory(addr, s->vram_size, s->vram_offset);
     }
+
+    s->map_addr = addr;
+    s->map_end = addr + VGA_RAM_SIZE;
+
+    vga_dirty_log_start(s);
 }
 
 void vga_common_init(VGAState *s, DisplayState *ds, uint8_t *vga_ram_base,

Modified: trunk/hw/vga_int.h
===================================================================
--- trunk/hw/vga_int.h  2008-11-24 19:36:26 UTC (rev 5792)
+++ trunk/hw/vga_int.h  2008-11-24 20:21:41 UTC (rev 5793)
@@ -102,6 +102,11 @@
     uint8_t *vram_ptr;                                                  \
     ram_addr_t vram_offset;                                             \
     unsigned int vram_size;                                             \
+    uint32_t lfb_addr;                                                  \
+    uint32_t lfb_end;                                                   \
+    uint32_t map_addr;                                                  \
+    uint32_t map_end;                                                   \
+    uint32_t lfb_vram_mapped; /* whether 0xa0000 is mapped as ram */    \
     unsigned long bios_offset;                                          \
     unsigned int bios_size;                                             \
     target_phys_addr_t base_ctrl;                                       \
@@ -189,6 +194,10 @@
 void vga_common_init(VGAState *s, DisplayState *ds, uint8_t *vga_ram_base,
                      ram_addr_t vga_ram_offset, int vga_ram_size);
 void vga_init(VGAState *s);
+
+void vga_dirty_log_start(VGAState *s);
+void vga_dirty_log_stop(VGAState *s);
+
 uint32_t vga_mem_readb(void *opaque, target_phys_addr_t addr);
 void vga_mem_writeb(void *opaque, target_phys_addr_t addr, uint32_t val);
 void vga_invalidate_scanlines(VGAState *s, int y1, int y2);