arm/arm64: KVM: Fix BE accesses to GICv2 EISR and ELRSR regs

The EIRSR and ELRSR registers are 32-bit registers on GICv2, and we
store these as an array of two such registers on the vgic vcpu struct.
However, we access them as a single 64-bit value or as a bitmap pointer
in the generic vgic code, which breaks BE support.

Instead, store them as u64 values on the vgic structure and do the
word-swapping in the assembly code, which already handles the byte order
for BE systems.

Tested-by: Victor Kamensky <victor.kamensky@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

2 files changed, 19 insertions, 23 deletions

diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
index 01124ef3690a..2935405ad22f 100644
--- a/virt/kvm/arm/vgic-v2.c
+++ b/virt/kvm/arm/vgic-v2.c
@@ -71,35 +71,17 @@ static void vgic_v2_sync_lr_elrsr(struct kvm_vcpu *vcpu, int lr,
                                   struct vgic_lr lr_desc)
 {
         if (!(lr_desc.state & LR_STATE_MASK))
-                set_bit(lr, (unsigned long *)vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr);
+                vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr |= (1ULL << lr);
 }
 
 static u64 vgic_v2_get_elrsr(const struct kvm_vcpu *vcpu)
 {
-        u64 val;
-
-#if BITS_PER_LONG == 64
-        val  = vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr[1];
-        val <<= 32;
-        val |= vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr[0];
-#else
-        val = *(u64 *)vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr;
-#endif
-        return val;
+        return vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr;
 }
 
 static u64 vgic_v2_get_eisr(const struct kvm_vcpu *vcpu)
 {
-        u64 val;
-
-#if BITS_PER_LONG == 64
-        val  = vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr[1];
-        val <<= 32;
-        val |= vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr[0];
-#else
-        val = *(u64 *)vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr;
-#endif
-        return val;
+        return vcpu->arch.vgic_cpu.vgic_v2.vgic_eisr;
 }
 
 static u32 vgic_v2_get_interrupt_status(const struct kvm_vcpu *vcpu)
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 382fb5a88b9c..3aaca49de325 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -145,6 +145,20 @@ static void vgic_free_bitmap(struct vgic_bitmap *b)
         b->shared = NULL;
 }
 
+/*
+ * Call this function to convert a u64 value to an unsigned long * bitmask
+ * in a way that works on both 32-bit and 64-bit LE and BE platforms.
+ *
+ * Warning: Calling this function may modify *val.
+ */
+static unsigned long *u64_to_bitmask(u64 *val)
+{
+#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 32
+        *val = (*val >> 32) | (*val << 32);
+#endif
+        return (unsigned long *)val;
+}
+
 static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x,
                                 int cpuid, u32 offset)
 {
@@ -1442,7 +1456,7 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
                  * active bit.
                  */
                 u64 eisr = vgic_get_eisr(vcpu);
-                unsigned long *eisr_ptr = (unsigned long *)&eisr;
+                unsigned long *eisr_ptr = u64_to_bitmask(&eisr);
                 int lr;
 
                 for_each_set_bit(lr, eisr_ptr, vgic->nr_lr) {
@@ -1505,7 +1519,7 @@ static void __kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 
         level_pending = vgic_process_maintenance(vcpu);
         elrsr = vgic_get_elrsr(vcpu);
-        elrsr_ptr = (unsigned long *)&elrsr;
+        elrsr_ptr = u64_to_bitmask(&elrsr);
 
         /* Clear mappings for empty LRs */
         for_each_set_bit(lr, elrsr_ptr, vgic->nr_lr) {