Re: [Qemu-devel] [PATCH 2/2] cpu_physical_memory_write_rom() needs to do TB invalidates

[David Gibson <dwg@au1.ibm.com>]

On Mon, Sep 10, 2012 at 03:27:45PM +0200, Andreas Färber wrote:
> Am 10.09.2012 04:30, schrieb David Gibson:
> > cpu_physical_memory_write_rom(), despite the name, can also be used to
> > write images into RAM - and will often be used that way if the machine
> > uses load_image_targphys() into RAM addresses.
> > 
> > However, cpu_physical_memory_write_rom(), unlike cpu_physical_memory_rw()
> > does invalidate any cached TBs which might be affected by the region
> 
> "doesn't"?
> 
> Otherwise doesn't look wrong.

Oops, comment updated.

>From 6b913afaf83f52ee787271827c84b492e8ac5895 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Wed, 22 Aug 2012 14:58:04 +1000
Subject: [PATCH] cpu_physical_memory_write_rom() needs to do TB invalidates

cpu_physical_memory_write_rom(), despite the name, can also be used to
write images into RAM - and will often be used that way if the machine
uses load_image_targphys() into RAM addresses.

However, cpu_physical_memory_write_rom(), unlike
cpu_physical_memory_rw() doesn't invalidate any cached TBs which might
be affected by the region written.

This was breaking reset (under full emu) on the pseries machine - we loaded
our firmware image into RAM, and while executing it rewrite the code at
the entry point (correctly causing a TB invalidate/refresh).  When we
reset the firmware image was reloaded, but the TB from the rewrite was
still active and caused us to get an illegal instruction trap.

This patch fixes the bug by duplicating the tb invalidate code from
cpu_physical_memory_rw() in cpu_physical_memory_write_rom().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 exec.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/exec.c b/exec.c
index 5834766..eff40d7 100644
--- a/exec.c
+++ b/exec.c
@@ -3523,6 +3523,13 @@ void cpu_physical_memory_write_rom(target_phys_addr_t addr,
             /* ROM/RAM case */
             ptr = qemu_get_ram_ptr(addr1);
             memcpy(ptr, buf, l);
+            if (!cpu_physical_memory_is_dirty(addr1)) {
+                /* invalidate code */
+                tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
+                /* set dirty bit */
+                cpu_physical_memory_set_dirty_flags(
+                    addr1, (0xff & ~CODE_DIRTY_FLAG));
+            }
             qemu_put_ram_ptr(ptr);
         }
         len -= l;
-- 
1.7.10.4

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson