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

On Fri, Feb 23, 2018 at 02:30:54PM +0000, Julien Grall wrote:

Hi Christoffer,

On 15/02/18 21:03, Christoffer Dall wrote:

quoted

@@ -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