Adamos Ttofari 10e4b5166d x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD ... Commit 672365477a ("x86/fpu: Update XFD state where required") and commit 8bf26758ca ("x86/fpu: Add XFD state to fpstate") introduced a per CPU variable xfd_state to keep the MSR_IA32_XFD value cached, in order to avoid unnecessary writes to the MSR. On CPU hotplug MSR_IA32_XFD is reset to the init_fpstate.xfd, which wipes out any stale state. But the per CPU cached xfd value is not reset, which brings them out of sync. As a consequence a subsequent xfd_update_state() might fail to update the MSR which in turn can result in XRSTOR raising a #NM in kernel space, which crashes the kernel. To fix this, introduce xfd_set_state() to write xfd_state together with MSR_IA32_XFD, and use it in all places that set MSR_IA32_XFD. Fixes: 672365477a ("x86/fpu: Update XFD state where required") Signed-off-by: Adamos Ttofari <attofari@amazon.de> Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20240322230439.456571-1-chang.seok.bae@intel.com Closes: https://lore.kernel.org/lkml/20230511152818.13839-1-attofari@amazon.de		2024-03-24 04:03:54 +01:00
..
bugs.c	x86/msr: Prepare for including <linux/percpu.h> into <asm/msr.h>	2024-03-04 12:01:39 +01:00
context.h	x86/fpu: Invalidate FPU state correctly on exec()	2023-08-24 11:01:45 +02:00
core.c	arch/x86: Fix typos	2024-01-03 11:46:22 +01:00
init.c	x86/fpu: Mark init functions __init	2023-06-16 10:16:01 +02:00
internal.h	x86/fpu/signal: Prepare for variable sigframe length	2021-10-26 10:18:09 +02:00
legacy.h	x86/fpu: Remove .fixup usage	2021-12-11 09:09:48 +01:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
regset.c	x86: Add PTRACE interface for shadow stack	2023-08-02 15:01:51 -07:00
signal.c	x86/fpu: Stop relying on userspace for info to fault in xsave buffer	2024-01-30 07:25:48 -08:00
xstate.c	x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD	2024-03-24 04:03:54 +01:00
xstate.h	x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD	2024-03-24 04:03:54 +01:00