[Qemu-devel] [PATCH 1/3] hw/arm_boot, exynos4210, highbank: Fix secondary boot GIC init

[Peter Maydell]

Fix the code in the secondary CPU boot stubs so that it correctly
initialises the GIC rather than relying on bugs or implementation
dependent aspects of the QEMU GIC implementation:
 * set the GIC_PMR.Priority field to all-ones, so that all
   interrupts are passed through. The default of all-zeroes
   means all interrupts are masked, and QEMU only booted because
   of a bug in the priority masking in our GIC implementation.
 * add a barrier after GIC setup and before WFI to ensure that
   GIC config is complete before we go into a possible low power
   state. This isn't needed with the software GIC model but could
   be required when using KVM and executing this code on the
   real hardware CPU.

Note that of the three secondary stub implementations, only
the common generic one needs to support both v6 and v7 DSB
encodings; highbank and exynos4210 will always be v7 CPUs.

Signed-off-by: Peter Maydell <address@hidden>
---
 hw/arm_boot.c   |   17 ++++++++++++++---
 hw/exynos4210.c |   10 +++++++---
 hw/highbank.c   |    7 +++++--
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/hw/arm_boot.c b/hw/arm_boot.c
index 92e2cab..ec3b8d5 100644
--- a/hw/arm_boot.c
+++ b/hw/arm_boot.c
@@ -44,11 +44,17 @@ static uint32_t bootloader[] = {
  * for an interprocessor interrupt and polling a configurable
  * location for the kernel secondary CPU entry point.
  */
+#define DSB_INSN 0xf57ff04f
+#define CP15_DSB_INSN 0xee070f9a /* mcr cp15, 0, r0, c7, c10, 4 */
+
 static uint32_t smpboot[] = {
-  0xe59f201c, /* ldr r2, gic_cpu_if */
-  0xe59f001c, /* ldr r0, startaddr */
+  0xe59f2028, /* ldr r2, gic_cpu_if */
+  0xe59f0028, /* ldr r0, startaddr */
   0xe3a01001, /* mov r1, #1 */
-  0xe5821000, /* str r1, [r2] */
+  0xe5821000, /* str r1, [r2] - set GICC_CTLR.Enable */
+  0xe3a010ff, /* mov r1, #0xff */
+  0xe5821004, /* str r1, [r2, 4] - set GIC_PMR.Priority to 0xff */
+  DSB_INSN,   /* dsb */
   0xe320f003, /* wfi */
   0xe5901000, /* ldr     r1, [r0] */
   0xe1110001, /* tst     r1, r1 */
@@ -65,6 +71,11 @@ static void default_write_secondary(ARMCPU *cpu,
     smpboot[ARRAY_SIZE(smpboot) - 1] = info->smp_bootreg_addr;
     smpboot[ARRAY_SIZE(smpboot) - 2] = info->gic_cpu_if_addr;
     for (n = 0; n < ARRAY_SIZE(smpboot); n++) {
+        /* Replace DSB with the pre-v7 DSB if necessary. */
+        if (!arm_feature(&cpu->env, ARM_FEATURE_V7) &&
+            smpboot[n] == DSB_INSN) {
+            smpboot[n] = CP15_DSB_INSN;
+        }
         smpboot[n] = tswap32(smpboot[n]);
     }
     rom_add_blob_fixed("smpboot", smpboot, sizeof(smpboot),
diff --git a/hw/exynos4210.c b/hw/exynos4210.c
index 00d4db8..22148cd 100644
--- a/hw/exynos4210.c
+++ b/hw/exynos4210.c
@@ -80,12 +80,16 @@ void exynos4210_write_secondary(ARMCPU *cpu,
 {
     int n;
     uint32_t smpboot[] = {
-        0xe59f3024, /* ldr r3, External gic_cpu_if */
-        0xe59f2024, /* ldr r2, Internal gic_cpu_if */
-        0xe59f0024, /* ldr r0, startaddr */
+        0xe59f3034, /* ldr r3, External gic_cpu_if */
+        0xe59f2034, /* ldr r2, Internal gic_cpu_if */
+        0xe59f0034, /* ldr r0, startaddr */
         0xe3a01001, /* mov r1, #1 */
         0xe5821000, /* str r1, [r2] */
         0xe5831000, /* str r1, [r3] */
+        0xe3a010ff, /* mov r1, #0xff */
+        0xe5821004, /* str r1, [r2, #4] */
+        0xe5831004, /* str r1, [r3, #4] */
+        0xf57ff04f, /* dsb */
         0xe320f003, /* wfi */
         0xe5901000, /* ldr     r1, [r0] */
         0xe1110001, /* tst     r1, r1 */
diff --git a/hw/highbank.c b/hw/highbank.c
index afbb005..447e57d 100644
--- a/hw/highbank.c
+++ b/hw/highbank.c
@@ -44,9 +44,12 @@ static void hb_write_secondary(ARMCPU *cpu, const struct 
arm_boot_info *info)
         0xe210000f, /* ands r0, r0, #0x0f */
         0xe3a03040, /* mov r3, #0x40 - jump address is 0x40 + 0x10 * core id */
         0xe0830200, /* add r0, r3, r0, lsl #4 */
-        0xe59f2018, /* ldr r2, privbase */
+        0xe59f2024, /* ldr r2, privbase */
         0xe3a01001, /* mov r1, #1 */
-        0xe5821100, /* str r1, [r2, #256] */
+        0xe5821100, /* str r1, [r2, #256] - set GICC_CTLR.Enable */
+        0xe3a010ff, /* mov r1, #0xff */
+        0xe5821104, /* str r1, [r2, #260] - set GICC_PMR.Priority to 0xff */
+        0xf57ff04f, /* dsb */
         0xe320f003, /* wfi */
         0xe5901000, /* ldr     r1, [r0] */
         0xe1110001, /* tst     r1, r1 */
-- 
1.7.9.5