KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h
new file mode 100644
index 000000000..f86a006d6
--- /dev/null
+++ b/include/kvm/arm_psci.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012,2013 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ */
+
+#ifndef __KVM_ARM_PSCI_H__
+#define __KVM_ARM_PSCI_H__
+
+#include <linux/kvm_host.h>
+#include <uapi/linux/psci.h>
+
+#define KVM_ARM_PSCI_0_1	PSCI_VERSION(0, 1)
+#define KVM_ARM_PSCI_0_2	PSCI_VERSION(0, 2)
+#define KVM_ARM_PSCI_1_0	PSCI_VERSION(1, 0)
+#define KVM_ARM_PSCI_1_1	PSCI_VERSION(1, 1)
+#define KVM_ARM_PSCI_1_2	PSCI_VERSION(1, 2)
+#define KVM_ARM_PSCI_1_3	PSCI_VERSION(1, 3)
+
+#define KVM_ARM_PSCI_LATEST	KVM_ARM_PSCI_1_3
+
+static inline int kvm_psci_version(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * Our PSCI implementation stays the same across versions from
+	 * v0.2 onward, only adding the few mandatory functions (such
+	 * as FEATURES with 1.0) that are required by newer
+	 * revisions. It is thus safe to return the latest, unless
+	 * userspace has instructed us otherwise.
+	 */
+	if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_PSCI_0_2)) {
+		if (vcpu->kvm->arch.psci_version)
+			return vcpu->kvm->arch.psci_version;
+
+		return KVM_ARM_PSCI_LATEST;
+	}
+
+	return KVM_ARM_PSCI_0_1;
+}
+
+/* Narrow the PSCI register arguments (r1 to r3) to 32 bits. */
+static inline void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	/*
+	 * Zero the input registers' upper 32 bits. They will be fully
+	 * zeroed on exit, so we're fine changing them in place.
+	 */
+	for (i = 1; i < 4; i++)
+		vcpu_set_reg(vcpu, i, lower_32_bits(vcpu_get_reg(vcpu, i)));
+}
+
+static inline bool kvm_psci_valid_affinity(struct kvm_vcpu *vcpu,
+					   unsigned long affinity)
+{
+	return !(affinity & ~MPIDR_HWID_BITMASK);
+}
+
+static inline unsigned long kvm_psci_affinity_mask(unsigned long affinity_level)
+{
+	if (affinity_level <= 3)
+		return MPIDR_HWID_BITMASK &
+			~((0x1UL << (affinity_level * MPIDR_LEVEL_BITS)) - 1);
+
+	return 0;
+}
+
+int kvm_psci_call(struct kvm_vcpu *vcpu);
+
+#endif /* __KVM_ARM_PSCI_H__ */