Subject: [PATCH v4 31/40] KVM: arm64: Move common VHE/non-VHE trap config in separate functions

From: [email-masked] (Christoffer Dall)
Date: Sun, 25 Feb 2018 22:29:43 +0100

On Fri, Feb 23, 2018 at 02:30:54PM +0000, Julien Grall wrote:
> Hi Christoffer,
> 
> On 15/02/18 21:03, Christoffer Dall wrote:
> >@@ -85,37 +123,14 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
> >  {
> >  	u64 hcr = vcpu->arch.hcr_el2;
> >-	/*
> >-	 * We are about to set CPTR_EL2.TFP to trap all floating point
> >-	 * register accesses to EL2, however, the ARM ARM clearly states that
> >-	 * traps are only taken to EL2 if the operation would not otherwise
> >-	 * trap to EL1.  Therefore, always make sure that for 32-bit guests,
> >-	 * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit.
> >-	 * If FP/ASIMD is not implemented, FPEXC is UNDEFINED and any access to
> >-	 * it will cause an exception.
> >-	 */
> >-	if (vcpu_el1_is_32bit(vcpu) && system_supports_fpsimd()) {
> >-		write_sysreg(1 << 30, fpexc32_el2);
> >-		isb();
> >-	}
> >+	write_sysreg(hcr, hcr_el2);
> >  	if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN) && (hcr & HCR_VSE))
> >  		write_sysreg_s(vcpu->arch.vsesr_el2, SYS_VSESR_EL2);
> >-	write_sysreg(hcr, hcr_el2);
> 
> OOI, any reason to move the write to HCR_EL2 just before the if?
> 

Just to keep the two lines together where we read the value from the
vcpu structure and write it to hardware.  It's hard to tell from this
patch, but I think it looks nicer in the end.

Thanks,
-Christoffer