5.15-stable review patch. If anyone has any objections, please let me know.
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From: Marc Zyngier maz@kernel.org
[ Upstream commit d52d165d67c5aa26c8c89909003c94a66492d23d ]
On each vcpu load, we set the KVM_ARM64_HOST_SVE_ENABLED flag if SVE is enabled for EL0 on the host. This is used to restore the correct state on vpcu put.
However, it appears that nothing ever clears this flag. Once set, it will stick until the vcpu is destroyed, which has the potential to spuriously enable SVE for userspace.
We probably never saw the issue because no VMM uses SVE, but that's still pretty bad. Unconditionally clearing the flag on vcpu load addresses the issue.
Fixes: 8383741ab2e7 ("KVM: arm64: Get rid of host SVE tracking/saving") Signed-off-by: Marc Zyngier maz@kernel.org Cc: stable@vger.kernel.org Reviewed-by: Mark Brown broonie@kernel.org Link: https://lore.kernel.org/r/20220528113829.1043361-2-maz@kernel.org Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kvm/fpsimd.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -75,6 +75,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc vcpu->arch.flags &= ~KVM_ARM64_FP_ENABLED; vcpu->arch.flags |= KVM_ARM64_FP_HOST;
+ vcpu->arch.flags &= ~KVM_ARM64_HOST_SVE_ENABLED; if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED; }