On 2020-05-26 17:28, James Morse wrote:

Hi Marc,

On 22/04/2020 13:00, Marc Zyngier wrote:

quoted

Extract the direct HW accessors for later reuse.

quoted

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 51db934702b64..46f218982df8c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

quoted

+u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg)
+{
+	u64 val = 0x8badf00d8badf00d;
+
+	if (!vcpu->arch.sysregs_loaded_on_cpu) {
+		goto memory_read;
 	}

-immediate_write:
+	if (__vcpu_read_sys_reg_from_cpu(reg, &val))
+		return val;
+
+memory_read:
+	return __vcpu_sys_reg(vcpu, reg);
+}

The goto here is a bit odd, is it just an artefact of how we got here?

That's because a lot of this changes when NV gets added to the mix,
see [1].

Is this easier on the eye?:
| u64 vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg)
| {
|	u64 val = 0x8badf00d8badf00d;
|
|	if (vcpu->arch.sysregs_loaded_on_cpu &&
|	    __vcpu_read_sys_reg_from_cpu(reg, &val))
|		return val;
|
| 	return __vcpu_sys_reg(vcpu, reg);
| }

Definitely. I don't mind reworking the NV branch so that the label
gets introduced there.

quoted

+void vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg)
+{
+	if (!vcpu->arch.sysregs_loaded_on_cpu)
+		goto memory_write;
+
+	if (__vcpu_write_sys_reg_to_cpu(val, reg))
+		return;
+
+memory_write:
 	 __vcpu_sys_reg(vcpu, reg) = val;
 }

Again I think its clearer without the goto....


Regardless:
Reviewed-by: James Morse <james.morse@arm.com>

Thanks,

         M.

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=kvm-arm64/nv-5.7-rc1-WIP&id=11f3217d39a602cbfac7d08064c8b31afb57348e
-- 
Jazz is not dead. It just smells funny...

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