[Qemu-devel] [PATCH V2 2/2] target-arm: Guest cpu endianness determination for virtio KVM ARM/ARM64

[Pranavkumar Sawargaonkar <pranavkumar@linaro.org>]

This patch implements a fucntion pointer virtio_is_big_endian()
from "CPUClass" structure for arm/arm64.
Function arm_cpu_virtio_endianness() is added to determine and
return the guest cpu endianness to virtio.
This is required for running cross endian guests with virtio on ARM/ARM64.

Changelog:

V2:
- Change the patch to be used generically for both ARM and ARM64.
- Address the review comments received in v1.

V1:
- First patch in this series.
- http://lists.gnu.org/archive/html/qemu-devel/2014-10/msg03321.html

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
---
 target-arm/cpu.c | 27 +++++++++++++++++++++++++++
 target-arm/cpu.h |  2 ++
 2 files changed, 29 insertions(+)

diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index d3db279..7145e02 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -320,6 +320,32 @@ static void arm_cpu_kvm_set_irq(void *opaque, int irq, int level)
     kvm_set_irq(kvm_state, kvm_irq, level ? 1 : 0);
 #endif
 }
+
+static bool arm_cpu_virtio_endianness(CPUState *cs)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+    uint64_t sctlr;
+
+    cpu_synchronize_state(cs);
+
+    /* Check if we are running 32bit guest or not */
+    if (!is_a64(env)) {
+        return (env->pstate & CPSR_E) ? 1 : 0;
+    }
+
+    sctlr = env->cp15.sctlr_el[1];
+
+    if ((env->pstate & 0xf) == PSTATE_MODE_EL0t) {
+        sctlr &= SCTLR_E0E;
+    } else {
+        sctlr &= SCTLR_EE;
+    }
+
+    /* If BIG-ENDIAN return 1 */
+    return sctlr ? 1 : 0;
+}
+
 #endif
 
 static inline void set_feature(CPUARMState *env, int feature)
@@ -1157,6 +1183,7 @@ static void arm_cpu_class_init(ObjectClass *oc, void *data)
     cc->do_interrupt = arm_cpu_do_interrupt;
     cc->get_phys_page_debug = arm_cpu_get_phys_page_debug;
     cc->vmsd = &vmstate_arm_cpu;
+    cc->virtio_is_big_endian = arm_cpu_virtio_endianness;
 #endif
     cc->gdb_num_core_regs = 26;
     cc->gdb_core_xml_file = "arm-core.xml";
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 7ba55f0..f32a5b6 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -32,6 +32,8 @@
 #  define ELF_MACHINE EM_ARM
 #endif
 
+#define TARGET_IS_BIENDIAN 1
+
 #define CPUArchState struct CPUARMState
 
 #include "qemu-common.h"
-- 
1.9.1