linux-kernel - [GIT PULL] x86 fixes

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Message-ID: <ZOo8XxiWEKL+BJeB@gmail.com>
Date:   Sat, 26 Aug 2023 19:54:39 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [GIT PULL] x86 fixes

Linus,

Please pull the latest x86/urgent git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2023-08-26

   # HEAD: 2c66ca3949dc701da7f4c9407f2140ae425683a5 x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4

Fix an FPU invalidation bug on exec(), and fix a performance
regression due to a missing setting of X86_FEATURE_OSXSAVE.

 Thanks,

	Ingo

------------------>
Feng Tang (1):
      x86/fpu: Set X86_FEATURE_OSXSAVE feature after enabling OSXSAVE in CR4

Rick Edgecombe (1):
      x86/fpu: Invalidate FPU state correctly on exec()


 arch/x86/kernel/fpu/context.h | 3 +--
 arch/x86/kernel/fpu/core.c    | 2 +-
 arch/x86/kernel/fpu/xstate.c  | 7 +++++++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/fpu/context.h b/arch/x86/kernel/fpu/context.h
index af5cbdd9bd29..f6d856bd50bc 100644
--- a/arch/x86/kernel/fpu/context.h
+++ b/arch/x86/kernel/fpu/context.h
@@ -19,8 +19,7 @@
  * FPU state for a task MUST let the rest of the kernel know that the
  * FPU registers are no longer valid for this task.
  *
- * Either one of these invalidation functions is enough. Invalidate
- * a resource you control: CPU if using the CPU for something else
+ * Invalidate a resource you control: CPU if using the CPU for something else
  * (with preemption disabled), FPU for the current task, or a task that
  * is prevented from running by the current task.
  */
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 1015af1ae562..98e507cc7d34 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -679,7 +679,7 @@ static void fpu_reset_fpregs(void)
 	struct fpu *fpu = &current->thread.fpu;
 
 	fpregs_lock();
-	fpu__drop(fpu);
+	__fpu_invalidate_fpregs_state(fpu);
 	/*
 	 * This does not change the actual hardware registers. It just
 	 * resets the memory image and sets TIF_NEED_FPU_LOAD so a
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 0bab497c9436..1afbc4866b10 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -882,6 +882,13 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
 		goto out_disable;
 	}
 
+	/*
+	 * CPU capabilities initialization runs before FPU init. So
+	 * X86_FEATURE_OSXSAVE is not set. Now that XSAVE is completely
+	 * functional, set the feature bit so depending code works.
+	 */
+	setup_force_cpu_cap(X86_FEATURE_OSXSAVE);
+
 	print_xstate_offset_size();
 	pr_info("x86/fpu: Enabled xstate features 0x%llx, context size is %d bytes, using '%s' format.\n",
 		fpu_kernel_cfg.max_features,