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authorMarc Zyngier <marc.zyngier@arm.com>2018-08-23 11:51:43 +0100
committerChristoffer Dall <christoffer.dall@arm.com>2018-09-07 15:05:50 +0200
commit7d14919c0d475a795c0127631ac8ecb2b0f31831 (patch)
tree84f8fac05bacd87e4e448acec0562305c927fbc0
parent694556d54f354d3fe43bb2e61fd6103cca2638a4 (diff)
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arm64: KVM: Only force FPEXC32_EL2.EN if trapping FPSIMD
If trapping FPSIMD in the context of an AArch32 guest, it is critical to set FPEXC32_EL2.EN to 1 so that the trapping is taken to EL2 and not EL1. Conversely, it is just as critical *not* to set FPEXC32_EL2.EN to 1 if we're not going to trap FPSIMD, as we then corrupt the existing VFP state. Moving the call to __activate_traps_fpsimd32 to the point where we know for sure that we are going to trap ensures that we don't set that bit spuriously. Fixes: e6b673b741ea ("KVM: arm64: Optimise FPSIMD handling to reduce guest/host thrashing") Cc: stable@vger.kernel.org # v4.18 Cc: Dave Martin <dave.martin@arm.com> Reported-by: Alexander Graf <agraf@suse.de> Tested-by: Alexander Graf <agraf@suse.de> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
-rw-r--r--arch/arm64/kvm/hyp/switch.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index d496ef579859..ca46153d7915 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -98,8 +98,10 @@ static void activate_traps_vhe(struct kvm_vcpu *vcpu)
val = read_sysreg(cpacr_el1);
val |= CPACR_EL1_TTA;
val &= ~CPACR_EL1_ZEN;
- if (!update_fp_enabled(vcpu))
+ if (!update_fp_enabled(vcpu)) {
val &= ~CPACR_EL1_FPEN;
+ __activate_traps_fpsimd32(vcpu);
+ }
write_sysreg(val, cpacr_el1);
@@ -114,8 +116,10 @@ static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu)
val = CPTR_EL2_DEFAULT;
val |= CPTR_EL2_TTA | CPTR_EL2_TZ;
- if (!update_fp_enabled(vcpu))
+ if (!update_fp_enabled(vcpu)) {
val |= CPTR_EL2_TFP;
+ __activate_traps_fpsimd32(vcpu);
+ }
write_sysreg(val, cptr_el2);
}
@@ -129,7 +133,6 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
if (cpus_have_const_cap(ARM64_HAS_RAS_EXTN) && (hcr & HCR_VSE))
write_sysreg_s(vcpu->arch.vsesr_el2, SYS_VSESR_EL2);
- __activate_traps_fpsimd32(vcpu);
if (has_vhe())
activate_traps_vhe(vcpu);
else