KVM uses swab32() when mediating GIC MMIO accesses if the GICV is badly
aligned, and the host and guest differ in endianness.
arm64 doesn't provide a __arch_swab32(), so __fswab32() is always backed
by the macro implementation that the compiler reduces to a single
instruction. But the static-inline causes problems for KVM if the compiler
chooses not to inline this function, it may not be located in the
__hyp_text where __vgic_v2_perform_cpuif_access() needs it.
Create our own __kvm_swab32() macro that calls ___constant_swab32()
directly. This way we know it will always be inlined.
Signed-off-by: James Morse <james.morse@xxxxxxx>
---
arch/arm64/include/asm/kvm_hyp.h | 7 +++++++
arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c | 4 ++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index a3a6a2ba9a63..fe57f60f06a8 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -47,6 +47,13 @@
#define read_sysreg_el2(r) read_sysreg_elx(r, _EL2, _EL1)
#define write_sysreg_el2(v,r) write_sysreg_elx(v, r, _EL2, _EL1)
+/*
+ * Without an __arch_swab32(), we fall back to ___constant_swab32(), but the
+ * static inline can allow the compiler to out-of-line this. KVM always wants
+ * the macro version as its always inlined.
+ */
+#define __kvm_swab32(x) ___constant_swab32(x)
+
int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu);
void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
index 29ee1feba4eb..4f3a087e36d5 100644
--- a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
+++ b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
@@ -69,14 +69,14 @@ int __hyp_text __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu)
u32 data = vcpu_get_reg(vcpu, rd);
if (__is_be(vcpu)) {
/* guest pre-swabbed data, undo this for writel() */
- data = swab32(data);
+ data = __kvm_swab32(data);
}
writel_relaxed(data, addr);
} else {
u32 data = readl_relaxed(addr);
if (__is_be(vcpu)) {
/* guest expects swabbed data */
- data = swab32(data);
+ data = __kvm_swab32(data);
}
vcpu_set_reg(vcpu, rd, data);
}
--
2.24.1
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