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, 56 insertions, 0 deletions

diff --git a/security/integrity/efi_secureboot.c b/security/integrity/efi_secureboot.c
new file mode 100644
index 000000000..bfd4260a8
--- /dev/null
+++ b/security/integrity/efi_secureboot.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-1.0+
+/*
+ * Copyright (C) 2018 IBM Corporation
+ */
+#include <linux/efi.h>
+#include <linux/secure_boot.h>
+#include <asm/efi.h>
+
+#ifndef arch_efi_boot_mode
+#define arch_efi_boot_mode efi_secureboot_mode_unset
+#endif
+
+static enum efi_secureboot_mode get_sb_mode(void)
+{
+	enum efi_secureboot_mode mode;
+
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
+		pr_info("integrity: secureboot mode unknown, no efi\n");
+		return efi_secureboot_mode_unknown;
+	}
+
+	mode = efi_get_secureboot_mode(efi.get_variable);
+	if (mode == efi_secureboot_mode_disabled)
+		pr_info("integrity: secureboot mode disabled\n");
+	else if (mode == efi_secureboot_mode_unknown)
+		pr_info("integrity: secureboot mode unknown\n");
+	else
+		pr_info("integrity: secureboot mode enabled\n");
+	return mode;
+}
+
+/*
+ * Query secure boot status
+ *
+ * Note don't call this function too early e.g. in __setup hook otherwise the
+ * kernel may hang when calling efi_get_secureboot_mode.
+ *
+ */
+bool arch_get_secureboot(void)
+{
+	static enum efi_secureboot_mode sb_mode;
+	static bool initialized;
+
+	if (!initialized && efi_enabled(EFI_BOOT)) {
+		sb_mode = arch_efi_boot_mode;
+
+		if (sb_mode == efi_secureboot_mode_unset)
+			sb_mode = get_sb_mode();
+		initialized = true;
+	}
+
+	if (sb_mode == efi_secureboot_mode_enabled)
+		return true;
+	else
+		return false;
+}