KVM: arm64: Define our own swab32() to avoid a uapi static inline (8c2d146e) · Commits · 戴 / test

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

arch/arm64/include/asm/kvm_hyp.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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);

arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

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