[GIT PULL] x86 fixes

Ingo Molnar
2023-08-26T17:55:51Z

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* FPU registers are no longer valid for this task.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,