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Commit dedf97e8 authored Aug 01, 2014 by Marc Zyngier Committed by Christoffer Dall Aug 01, 2014

arm64: KVM: fix 64bit CP15 VM access for 32bit guests



Commit f0a3eaff (ARM64: KVM: fix big endian issue in
access_vm_reg for 32bit guest) changed the way we handle CP15
VM accesses, so that all 64bit accesses are done via vcpu_sys_reg.

This looks like a good idea as it solves indianness issues in an
elegant way, except for one small detail: the register index is
doesn't refer to the same array! We end up corrupting some random
data structure instead.

Fix this by reverting to the original code, except for the introduction
of a vcpu_cp15_64_high macro that deals with the endianness thing.

Tested on Juno with 32bit SMP guests.

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

parent fb3ec679

arch/arm64/include/asm/kvm_host.h

+4 −2

Original line number	Original line	Diff line number	Diff line
	@@ -149,9 +149,11 @@ struct kvm_vcpu_arch {
	#define vcpu_cp15(v,r) ((v)->arch.ctxt.copro[(r)])		#define vcpu_cp15(v,r) ((v)->arch.ctxt.copro[(r)])

	#ifdef CONFIG_CPU_BIG_ENDIAN		#ifdef CONFIG_CPU_BIG_ENDIAN
	#define vcpu_cp15_64_low(v,r) ((v)->arch.ctxt.copro[((r) + 1)])		#define vcpu_cp15_64_high(v,r) vcpu_cp15((v),(r))
			#define vcpu_cp15_64_low(v,r) vcpu_cp15((v),(r) + 1)
	#else		#else
	#define vcpu_cp15_64_low(v,r) ((v)->arch.ctxt.copro[((r) + 0)])		#define vcpu_cp15_64_high(v,r) vcpu_cp15((v),(r) + 1)
			#define vcpu_cp15_64_low(v,r) vcpu_cp15((v),(r))
	#endif		#endif

	struct kvm_vm_stat {		struct kvm_vm_stat {

arch/arm64/kvm/sys_regs.c

+5 −2

Original line number	Original line	Diff line number	Diff line
	@@ -135,10 +135,13 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
	BUG_ON(!p->is_write);		BUG_ON(!p->is_write);

	val = *vcpu_reg(vcpu, p->Rt);		val = *vcpu_reg(vcpu, p->Rt);
	if (!p->is_aarch32 \|\| !p->is_32bit)		if (!p->is_aarch32) {
	vcpu_sys_reg(vcpu, r->reg) = val;		vcpu_sys_reg(vcpu, r->reg) = val;
	else		} else {
			if (!p->is_32bit)
			vcpu_cp15_64_high(vcpu, r->reg) = val >> 32;
	vcpu_cp15_64_low(vcpu, r->reg) = val & 0xffffffffUL;		vcpu_cp15_64_low(vcpu, r->reg) = val & 0xffffffffUL;
			}

	return true;		return true;
	}		}