From 69f6ed1d14c6bcf712f4bb22a231c15eeab401e7 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 22 Oct 2021 20:55:51 +0200 Subject: x86/fpu: Provide infrastructure for KVM FPU cleanup For the upcoming AMX support it's necessary to do a proper integration with KVM. Currently KVM allocates two FPU structs which are used for saving the user state of the vCPU thread and restoring the guest state when entering vcpu_run() and doing the reverse operation before leaving vcpu_run(). With the new fpstate mechanism this can be reduced to one extra buffer by swapping the fpstate pointer in current::thread::fpu. This makes the upcoming support for AMX and XFD simpler because then fpstate information (features, sizes, xfd) are always consistent and it does not require any nasty workarounds. Provide: - An allocator which initializes the state properly - A replacement for the existing FPU swap mechanim Aside of the reduced memory footprint, this also makes state switching more efficient when TIF_FPU_NEED_LOAD is set. It does not require a memcpy as the state is already correct in the to be swapped out fpstate. The existing interfaces will be removed once KVM is converted over. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211022185312.954684740@linutronix.de --- arch/x86/include/asm/fpu/api.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/x86/include/asm/fpu/api.h') diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index 9ce83148058f..de85bcaae0c3 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -135,9 +135,22 @@ extern void fpu_init_fpstate_user(struct fpu *fpu); extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature); /* KVM specific functions */ +extern bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu); +extern void fpu_free_guest_fpstate(struct fpu_guest *gfpu); +extern int fpu_swap_kvm_fpstate(struct fpu_guest *gfpu, bool enter_guest); extern void fpu_swap_kvm_fpu(struct fpu *save, struct fpu *rstor, u64 restore_mask); extern int fpu_copy_kvm_uabi_to_fpstate(struct fpu *fpu, const void *buf, u64 xcr0, u32 *pkru); extern void fpu_copy_fpstate_to_kvm_uabi(struct fpu *fpu, void *buf, unsigned int size, u32 pkru); +static inline void fpstate_set_confidential(struct fpu_guest *gfpu) +{ + gfpu->fpstate->is_confidential = true; +} + +static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) +{ + return gfpu->fpstate->is_confidential; +} + #endif /* _ASM_X86_FPU_API_H */ -- cgit v1.2.3