[tip: x86/fpu] x86/fpu: Provide struct fpu_config

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the x86/fpu branch of tip:

Commit-ID:     578971f4e228f386ad4d7ce16e979f2ed922de54
Gitweb:        https://git.kernel.org/tip/578971f4e228f386ad4d7ce16e979f2ed922de54
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Fri, 15 Oct 2021 01:09:29 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 21 Oct 2021 19:17:58 +02:00

x86/fpu: Provide struct fpu_config

Provide a struct to store information about the maximum supported and the
default feature set and buffer sizes for both user and kernel space.

This allows quick retrieval of this information for the upcoming support
for dynamically enabled features.

 [ bp: Add vertical spacing between the struct members. ]

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20211014230739.126107370@xxxxxxxxxxxxx
---
 arch/x86/include/asm/fpu/types.h | 42 +++++++++++++++++++++++++++++++-
 arch/x86/kernel/fpu/core.c       |  4 +++-
 2 files changed, 46 insertions(+)

diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 3a12e97..a32be07 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -378,4 +378,46 @@ struct fpu {
 	 */
 };
 
+/*
+ * FPU state configuration data. Initialized at boot time. Read only after init.
+ */
+struct fpu_state_config {
+	/*
+	 * @max_size:
+	 *
+	 * The maximum size of the register state buffer. Includes all
+	 * supported features except independent managed features.
+	 */
+	unsigned int		max_size;
+
+	/*
+	 * @default_size:
+	 *
+	 * The default size of the register state buffer. Includes all
+	 * supported features except independent managed features and
+	 * features which have to be requested by user space before usage.
+	 */
+	unsigned int		default_size;
+
+	/*
+	 * @max_features:
+	 *
+	 * The maximum supported features bitmap. Does not include
+	 * independent managed features.
+	 */
+	u64 max_features;
+
+	/*
+	 * @default_features:
+	 *
+	 * The default supported features bitmap. Does not include
+	 * independent managed features and features which have to
+	 * be requested by user space before usage.
+	 */
+	u64 default_features;
+};
+
+/* FPU state configuration information */
+extern struct fpu_state_config fpu_kernel_cfg, fpu_user_cfg;
+
 #endif /* _ASM_X86_FPU_H */
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index b497eca..3512bb2 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -25,6 +25,10 @@
 #define CREATE_TRACE_POINTS
 #include <asm/trace/fpu.h>
 
+/* The FPU state configuration data for kernel and user space */
+struct fpu_state_config	fpu_kernel_cfg __ro_after_init;
+struct fpu_state_config fpu_user_cfg __ro_after_init;
+
 /*
  * Represents the initial FPU state. It's mostly (but not completely) zeroes,
  * depending on the FPU hardware format: