[POC Seabios PATCH] seabios: use isolated SMM address space for relocation

[Igor Mammedov <imammedo@redhat.com>]

for purpose of demo SMRAM (at 0x30000) is aliased at a0000 in system address space
for easy initialization of SMI entry point.
Here is resulting debug output showing that RAM at 0x30000 is not affected
by SMM and only RAM in SMM adderss space is modified:

init smm
smm_relocate: before relocaten
smm_relocate: RAM codeentry 0
smm_relocate: RAM  cpu.i64.smm_base  0
smm_relocate: SMRAM  codeentry f000c831eac88c
smm_relocate: SMRAM  cpu.i64.smm_base  0
handle_smi cmd=0 smbase=0x00030000
smm_relocate: after relocaten
smm_relocate: RAM codeentry 0
smm_relocate: RAM  cpu.i64.smm_base  0
smm_relocate: SMRAM  codeentry f000c831eac88c
smm_relocate: SMRAM  cpu.i64.smm_base  a0000

Patch depends on QEMU POC patch that adds SMRAM at 0x30000 in SMM address space

PS:
configure bios with level 9 debugging and debug port

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 src/fw/smm.c | 43 +++++++++++++++++++------------------------
 1 file changed, 19 insertions(+), 24 deletions(-)

diff --git a/src/fw/smm.c b/src/fw/smm.c
index d90e43a9..27f9747e 100644
--- a/src/fw/smm.c
+++ b/src/fw/smm.c
@@ -140,21 +140,22 @@ extern void entry_smi(void);
                   | ((u64)((u32)entry_smi - BUILD_BIOS_ADDR) << 24))
 
 static void
-smm_save_and_copy(void)
+smm_relocate(void)
 {
-    // save original memory content
     struct smm_layout *initsmm = (void*)BUILD_SMM_INIT_ADDR;
     struct smm_layout *smm = (void*)BUILD_SMM_ADDR;
-    memcpy(&smm->cpu, &initsmm->cpu, sizeof(smm->cpu));
-    memcpy(&smm->codeentry, &initsmm->codeentry, sizeof(smm->codeentry));
 
-    // Setup code entry point.
-    initsmm->codeentry = SMI_INSN;
-}
+    dprintf(3, "smm_relocate: before relocaten\n");
+    dprintf(3, "smm_relocate: RAM codeentry %llx\n", initsmm->codeentry);
+    dprintf(3, "smm_relocate: RAM  cpu.i64.smm_base  %lx\n", initsmm->cpu.i64.smm_base);
+
+
+    /* BUILD_SMM_ADDR aliased to BUILD_SMM_INIT_ADDR in SMM AS
+     * so we could set SMI entry point there */
+    smm->codeentry = SMI_INSN;
+    dprintf(3, "smm_relocate: SMRAM  codeentry %llx\n", smm->codeentry);
+    dprintf(3, "smm_relocate: SMRAM  cpu.i64.smm_base  %lx\n", smm->cpu.i64.smm_base);
 
-static void
-smm_relocate_and_restore(void)
-{
     /* init APM status port */
     outb(0x01, PORT_SMI_STATUS);
 
@@ -165,15 +166,13 @@ smm_relocate_and_restore(void)
     while (inb(PORT_SMI_STATUS) != 0x00)
         ;
 
-    /* restore original memory content */
-    struct smm_layout *initsmm = (void*)BUILD_SMM_INIT_ADDR;
-    struct smm_layout *smm = (void*)BUILD_SMM_ADDR;
-    memcpy(&initsmm->cpu, &smm->cpu, sizeof(initsmm->cpu));
-    memcpy(&initsmm->codeentry, &smm->codeentry, sizeof(initsmm->codeentry));
-
-    // Setup code entry point.
-    smm->codeentry = SMI_INSN;
     wbinvd();
+
+    dprintf(3, "smm_relocate: after relocaten\n");
+    dprintf(3, "smm_relocate: RAM codeentry %llx\n", initsmm->codeentry);
+    dprintf(3, "smm_relocate: RAM  cpu.i64.smm_base  %lx\n", initsmm->cpu.i64.smm_base);
+    dprintf(3, "smm_relocate: SMRAM  codeentry %llx\n", smm->codeentry);
+    dprintf(3, "smm_relocate: SMRAM  cpu.i64.smm_base  %lx\n", smm->cpu.i64.smm_base);
 }
 
 // This code is hardcoded for PIIX4 Power Management device.
@@ -187,8 +186,6 @@ static void piix4_apmc_smm_setup(int isabdf, int i440_bdf)
     /* enable the SMM memory window */
     pci_config_writeb(i440_bdf, I440FX_SMRAM, 0x02 | 0x48);
 
-    smm_save_and_copy();
-
     /* enable SMI generation when writing to the APMC register */
     pci_config_writel(isabdf, PIIX_DEVACTB, value | PIIX_DEVACTB_APMC_EN);
 
@@ -196,7 +193,7 @@ static void piix4_apmc_smm_setup(int isabdf, int i440_bdf)
     value = inl(acpi_pm_base + PIIX_PMIO_GLBCTL);
     outl(value | PIIX_PMIO_GLBCTL_SMI_EN, acpi_pm_base + PIIX_PMIO_GLBCTL);
 
-    smm_relocate_and_restore();
+    smm_relocate();
 
     /* close the SMM memory window and enable normal SMM */
     pci_config_writeb(i440_bdf, I440FX_SMRAM, 0x02 | 0x08);
@@ -213,8 +210,6 @@ void ich9_lpc_apmc_smm_setup(int isabdf, int mch_bdf)
     /* enable the SMM memory window */
     pci_config_writeb(mch_bdf, Q35_HOST_BRIDGE_SMRAM, 0x02 | 0x48);
 
-    smm_save_and_copy();
-
     /* enable SMI generation when writing to the APMC register */
     outl(value | ICH9_PMIO_SMI_EN_APMC_EN | ICH9_PMIO_SMI_EN_GLB_SMI_EN,
          acpi_pm_base + ICH9_PMIO_SMI_EN);
@@ -224,7 +219,7 @@ void ich9_lpc_apmc_smm_setup(int isabdf, int mch_bdf)
     pci_config_writel(isabdf, ICH9_LPC_GEN_PMCON_1,
                       value | ICH9_LPC_GEN_PMCON_1_SMI_LOCK);
 
-    smm_relocate_and_restore();
+    smm_relocate();
 
     /* close the SMM memory window and enable normal SMM */
     pci_config_writeb(mch_bdf, Q35_HOST_BRIDGE_SMRAM, 0x02 | 0x08);
-- 
2.18.1