KVM: arm64: Define our own swab32() to avoid a uapi static inline

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@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200220165839.256881-3-james.morse@arm.com

1 files changed, 2 insertions, 2 deletions

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);
 	}