@@ -133,12 +133,10 @@ static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id)
ARM_SMCCC_SMC_64, \
0, ARM_SMCCC_FUNC_MASK)
-static void init_smccc_filter(struct kvm *kvm)
+static int kvm_smccc_filter_insert_reserved(struct kvm *kvm)
{
int r;
- mt_init(&kvm->arch.smccc_filter);
-
/*
* Prevent userspace from handling any SMCCC calls in the architecture
* range, avoiding the risk of misrepresenting Spectre mitigation status
@@ -148,14 +146,20 @@ static void init_smccc_filter(struct kvm *kvm)
SMC32_ARCH_RANGE_BEGIN, SMC32_ARCH_RANGE_END,
xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
GFP_KERNEL_ACCOUNT);
- WARN_ON_ONCE(r);
+ if (r)
+ goto out_destroy;
r = mtree_insert_range(&kvm->arch.smccc_filter,
SMC64_ARCH_RANGE_BEGIN, SMC64_ARCH_RANGE_END,
xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
GFP_KERNEL_ACCOUNT);
- WARN_ON_ONCE(r);
+ if (r)
+ goto out_destroy;
+ return 0;
+out_destroy:
+ mtree_destroy(&kvm->arch.smccc_filter);
+ return r;
}
static bool kvm_smccc_filter_configured(struct kvm *kvm)
@@ -189,6 +193,12 @@ static int kvm_smccc_set_filter(struct kvm *kvm, struct kvm_smccc_filter __user
goto out_unlock;
}
+ if (!kvm_smccc_filter_configured(kvm)) {
+ r = kvm_smccc_filter_insert_reserved(kvm);
+ if (WARN_ON_ONCE(r))
+ goto out_unlock;
+ }
+
r = mtree_insert_range(&kvm->arch.smccc_filter, start, end,
xa_mk_value(filter.action), GFP_KERNEL_ACCOUNT);
if (r)
@@ -392,7 +402,7 @@ void kvm_arm_init_hypercalls(struct kvm *kvm)
smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
- init_smccc_filter(kvm);
+ mt_init(&kvm->arch.smccc_filter);
}
void kvm_arm_teardown_hypercalls(struct kvm *kvm)
The reserved ranges are only useful for preventing userspace from adding a rule that intersects with functions we must handle in KVM. If userspace never writes to the SMCCC filter than this is all just wasted work/memory. Insert reserved ranges on the first call to KVM_ARM_VM_SMCCC_FILTER. Signed-off-by: Oliver Upton <oliver.upton@linux.dev> --- arch/arm64/kvm/hypercalls.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)