[Qemu-devel] [PATCH v4 2/5] Preserve memory content during SMM init.

[Gleb Natapov <gleb@redhat.com>]

Signed-off-by: Gleb Natapov <gleb@redhat.com>
---

 bios/rombios32.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/bios/rombios32.c b/bios/rombios32.c
index 7b354a8..7075aa9 100644
--- a/bios/rombios32.c
+++ b/bios/rombios32.c
@@ -731,6 +731,12 @@ static void smm_init(PCIDevice *d)
     value = pci_config_readl(d, 0x58);
     if ((value & (1 << 25)) == 0) {
 
+        /* enable the SMM memory window */
+        pci_config_writeb(&i440_pcidev, 0x72, 0x02 | 0x48);
+
+        /* save original memory content */
+        memcpy((void *)0xa8000, (void *)0x38000, 0x8000);
+
         /* copy the SMM relocation code */
         memcpy((void *)0x38000, &smm_relocation_start,
                &smm_relocation_end - &smm_relocation_start);
@@ -747,8 +753,8 @@ static void smm_init(PCIDevice *d)
         /* wait until SMM code executed */
         while (inb(0xb3) != 0x00);
 
-        /* enable the SMM memory window */
-        pci_config_writeb(&i440_pcidev, 0x72, 0x02 | 0x48);
+        /* restore original memory content */
+        memcpy((void *)0x38000, (void *)0xa8000, 0x8000);
 
         /* copy the SMM code */
         memcpy((void *)0xa8000, &smm_code_start,