This takes a stab at sizing the xsave buffer so that it will work for AVX-512 systems. The logic is explained in the comment.
Cc: Linus Torvalds <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Linux Kernel Mailing List <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: leg Nesterov <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ross Zwisler <[email protected]> --- b/arch/x86/include/asm/fpu/types.h | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff -puN arch/x86/include/asm/fpu/types.h~enlarge-init-fpu-buf arch/x86/include/asm/fpu/types.h --- a/arch/x86/include/asm/fpu/types.h~enlarge-init-fpu-buf 2015-07-16 01:11:03.301028886 -0700 +++ b/arch/x86/include/asm/fpu/types.h 2015-07-16 01:11:03.304029021 -0700 @@ -159,10 +159,19 @@ struct xstate_header { u64 reserved[6]; } __attribute__((packed)); -/* New processor state extensions should be added here: */ -#define XSTATE_RESERVE (sizeof(struct ymmh_struct) + \ - sizeof(struct lwp_struct) + \ - sizeof(struct mpx_struct) ) +/* + * The largest xsave buffer known today is 2752 bytes on a system + * implementing AVX-512. This includes the 512-byte i387 state + * and 64-byte header. We add a small amount of padding in case + * an implementation adds some padding or wastes some space. + * + * Note, if we overflow this, we will disable XSAVE completely. + * + * Also, note that the real size we need is enumerated by + * cpuid leaves and can not be known at compile time. + */ +#define XSTATE_MAX_SIZE (2752 + 256) + /* * This is our most modern FPU state format, as saved by the XSAVE * and restored by the XRSTOR instructions. @@ -172,9 +181,13 @@ struct xstate_header { * Not all CPUs support all the extensions. */ struct xregs_state { - struct fxregs_state i387; - struct xstate_header header; - u8 __reserved[XSTATE_RESERVE]; + union { + struct { + struct fxregs_state i387; + struct xstate_header header; + }; + u8 __reserved[XSTATE_MAX_SIZE]; + }; } __attribute__ ((packed, aligned (64))); /* _ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
