1 files changed, 315 insertions, 77 deletions

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 7ada7bd03a3272..8ea306b1bf8ec1 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -6,8 +6,9 @@
  *  General FPU state handling cleanups
  *	Gareth Hughes <gareth@valinux.com>, May 2000
  */
-#include <asm/fpu/internal.h>
+#include <asm/fpu/api.h>
 #include <asm/fpu/regset.h>
+#include <asm/fpu/sched.h>
 #include <asm/fpu/signal.h>
 #include <asm/fpu/types.h>
 #include <asm/traps.h>
@@ -15,15 +16,30 @@
 
 #include <linux/hardirq.h>
 #include <linux/pkeys.h>
+#include <linux/vmalloc.h>
+
+#include "context.h"
+#include "internal.h"
+#include "legacy.h"
+#include "xstate.h"
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/fpu.h>
 
+#ifdef CONFIG_X86_64
+DEFINE_STATIC_KEY_FALSE(__fpu_state_size_dynamic);
+DEFINE_PER_CPU(u64, xfd_state);
+#endif
+
+/* The FPU state configuration data for kernel and user space */
+struct fpu_state_config	fpu_kernel_cfg __ro_after_init;
+struct fpu_state_config fpu_user_cfg __ro_after_init;
+
 /*
  * Represents the initial FPU state. It's mostly (but not completely) zeroes,
  * depending on the FPU hardware format:
  */
-union fpregs_state init_fpstate __ro_after_init;
+struct fpstate init_fpstate __ro_after_init;
 
 /*
  * Track whether the kernel is using the FPU state
@@ -83,7 +99,7 @@ bool irq_fpu_usable(void)
 EXPORT_SYMBOL(irq_fpu_usable);
 
 /*
- * Save the FPU register state in fpu->state. The register state is
+ * Save the FPU register state in fpu->fpstate->regs. The register state is
  * preserved.
  *
  * Must be called with fpregs_lock() held.
@@ -99,19 +115,19 @@ EXPORT_SYMBOL(irq_fpu_usable);
 void save_fpregs_to_fpstate(struct fpu *fpu)
 {
 	if (likely(use_xsave())) {
-		os_xsave(&fpu->state.xsave);
+		os_xsave(fpu->fpstate);
 
 		/*
 		 * AVX512 state is tracked here because its use is
 		 * known to slow the max clock speed of the core.
 		 */
-		if (fpu->state.xsave.header.xfeatures & XFEATURE_MASK_AVX512)
+		if (fpu->fpstate->regs.xsave.header.xfeatures & XFEATURE_MASK_AVX512)
 			fpu->avx512_timestamp = jiffies;
 		return;
 	}
 
 	if (likely(use_fxsr())) {
-		fxsave(&fpu->state.fxsave);
+		fxsave(&fpu->fpstate->regs.fxsave);
 		return;
 	}
 
@@ -119,12 +135,11 @@ void save_fpregs_to_fpstate(struct fpu *fpu)
 	 * Legacy FPU register saving, FNSAVE always clears FPU registers,
 	 * so we have to reload them from the memory state.
 	 */
-	asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->state.fsave));
-	frstor(&fpu->state.fsave);
+	asm volatile("fnsave %[fp]; fwait" : [fp] "=m" (fpu->fpstate->regs.fsave));
+	frstor(&fpu->fpstate->regs.fsave);
 }
-EXPORT_SYMBOL(save_fpregs_to_fpstate);
 
-void __restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
+void restore_fpregs_from_fpstate(struct fpstate *fpstate, u64 mask)
 {
 	/*
 	 * AMD K7/K8 and later CPUs up to Zen don't save/restore
@@ -141,15 +156,181 @@ void __restore_fpregs_from_fpstate(union fpregs_state *fpstate, u64 mask)
 	}
 
 	if (use_xsave()) {
-		os_xrstor(&fpstate->xsave, mask);
+		/*
+		 * Dynamically enabled features are enabled in XCR0, but
+		 * usage requires also that the corresponding bits in XFD
+		 * are cleared.  If the bits are set then using a related
+		 * instruction will raise #NM. This allows to do the
+		 * allocation of the larger FPU buffer lazy from #NM or if
+		 * the task has no permission to kill it which would happen
+		 * via #UD if the feature is disabled in XCR0.
+		 *
+		 * XFD state is following the same life time rules as
+		 * XSTATE and to restore state correctly XFD has to be
+		 * updated before XRSTORS otherwise the component would
+		 * stay in or go into init state even if the bits are set
+		 * in fpstate::regs::xsave::xfeatures.
+		 */
+		xfd_update_state(fpstate);
+
+		/*
+		 * Restoring state always needs to modify all features
+		 * which are in @mask even if the current task cannot use
+		 * extended features.
+		 *
+		 * So fpstate->xfeatures cannot be used here, because then
+		 * a feature for which the task has no permission but was
+		 * used by the previous task would not go into init state.
+		 */
+		mask = fpu_kernel_cfg.max_features & mask;
+
+		os_xrstor(fpstate, mask);
 	} else {
 		if (use_fxsr())
-			fxrstor(&fpstate->fxsave);
+			fxrstor(&fpstate->regs.fxsave);
 		else
-			frstor(&fpstate->fsave);
+			frstor(&fpstate->regs.fsave);
 	}
 }
-EXPORT_SYMBOL_GPL(__restore_fpregs_from_fpstate);
+
+void fpu_reset_from_exception_fixup(void)
+{
+	restore_fpregs_from_fpstate(&init_fpstate, XFEATURE_MASK_FPSTATE);
+}
+
+#if IS_ENABLED(CONFIG_KVM)
+static void __fpstate_reset(struct fpstate *fpstate);
+
+bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
+{
+	struct fpstate *fpstate;
+	unsigned int size;
+
+	size = fpu_user_cfg.default_size + ALIGN(offsetof(struct fpstate, regs), 64);
+	fpstate = vzalloc(size);
+	if (!fpstate)
+		return false;
+
+	__fpstate_reset(fpstate);
+	fpstate_init_user(fpstate);
+	fpstate->is_valloc	= true;
+	fpstate->is_guest	= true;
+
+	gfpu->fpstate = fpstate;
+	return true;
+}
+EXPORT_SYMBOL_GPL(fpu_alloc_guest_fpstate);
+
+void fpu_free_guest_fpstate(struct fpu_guest *gfpu)
+{
+	struct fpstate *fps = gfpu->fpstate;
+
+	if (!fps)
+		return;
+
+	if (WARN_ON_ONCE(!fps->is_valloc || !fps->is_guest || fps->in_use))
+		return;
+
+	gfpu->fpstate = NULL;
+	vfree(fps);
+}
+EXPORT_SYMBOL_GPL(fpu_free_guest_fpstate);
+
+int fpu_swap_kvm_fpstate(struct fpu_guest *guest_fpu, bool enter_guest)
+{
+	struct fpstate *guest_fps = guest_fpu->fpstate;
+	struct fpu *fpu = &current->thread.fpu;
+	struct fpstate *cur_fps = fpu->fpstate;
+
+	fpregs_lock();
+	if (!cur_fps->is_confidential && !test_thread_flag(TIF_NEED_FPU_LOAD))
+		save_fpregs_to_fpstate(fpu);
+
+	/* Swap fpstate */
+	if (enter_guest) {
+		fpu->__task_fpstate = cur_fps;
+		fpu->fpstate = guest_fps;
+		guest_fps->in_use = true;
+	} else {
+		guest_fps->in_use = false;
+		fpu->fpstate = fpu->__task_fpstate;
+		fpu->__task_fpstate = NULL;
+	}
+
+	cur_fps = fpu->fpstate;
+
+	if (!cur_fps->is_confidential) {
+		/* Includes XFD update */
+		restore_fpregs_from_fpstate(cur_fps, XFEATURE_MASK_FPSTATE);
+	} else {
+		/*
+		 * XSTATE is restored by firmware from encrypted
+		 * memory. Make sure XFD state is correct while
+		 * running with guest fpstate
+		 */
+		xfd_update_state(cur_fps);
+	}
+
+	fpregs_mark_activate();
+	fpregs_unlock();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fpu_swap_kvm_fpstate);
+
+void fpu_copy_guest_fpstate_to_uabi(struct fpu_guest *gfpu, void *buf,
+				    unsigned int size, u32 pkru)
+{
+	struct fpstate *kstate = gfpu->fpstate;
+	union fpregs_state *ustate = buf;
+	struct membuf mb = { .p = buf, .left = size };
+
+	if (cpu_feature_enabled(X86_FEATURE_XSAVE)) {
+		__copy_xstate_to_uabi_buf(mb, kstate, pkru, XSTATE_COPY_XSAVE);
+	} else {
+		memcpy(&ustate->fxsave, &kstate->regs.fxsave,
+		       sizeof(ustate->fxsave));
+		/* Make it restorable on a XSAVE enabled host */
+		ustate->xsave.header.xfeatures = XFEATURE_MASK_FPSSE;
+	}
+}
+EXPORT_SYMBOL_GPL(fpu_copy_guest_fpstate_to_uabi);
+
+int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf,
+				   u64 xcr0, u32 *vpkru)
+{
+	struct fpstate *kstate = gfpu->fpstate;
+	const union fpregs_state *ustate = buf;
+	struct pkru_state *xpkru;
+	int ret;
+
+	if (!cpu_feature_enabled(X86_FEATURE_XSAVE)) {
+		if (ustate->xsave.header.xfeatures & ~XFEATURE_MASK_FPSSE)
+			return -EINVAL;
+		if (ustate->fxsave.mxcsr & ~mxcsr_feature_mask)
+			return -EINVAL;
+		memcpy(&kstate->regs.fxsave, &ustate->fxsave, sizeof(ustate->fxsave));
+		return 0;
+	}
+
+	if (ustate->xsave.header.xfeatures & ~xcr0)
+		return -EINVAL;
+
+	ret = copy_uabi_from_kernel_to_xstate(kstate, ustate);
+	if (ret)
+		return ret;
+
+	/* Retrieve PKRU if not in init state */
+	if (kstate->regs.xsave.header.xfeatures & XFEATURE_MASK_PKRU) {
+		xpkru = get_xsave_addr(&kstate->regs.xsave, XFEATURE_PKRU);
+		*vpkru = xpkru->pkru;
+	}
+
+	/* Ensure that XCOMP_BV is set up for XSAVES */
+	xstate_init_xcomp_bv(&kstate->regs.xsave, kstate->xfeatures);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fpu_copy_uabi_to_guest_fpstate);
+#endif /* CONFIG_KVM */
 
 void kernel_fpu_begin_mask(unsigned int kfpu_mask)
 {
@@ -203,52 +384,88 @@ void fpu_sync_fpstate(struct fpu *fpu)
 	fpregs_unlock();
 }
 
-static inline void fpstate_init_xstate(struct xregs_state *xsave)
+static inline unsigned int init_fpstate_copy_size(void)
 {
-	/*
-	 * XRSTORS requires these bits set in xcomp_bv, or it will
-	 * trigger #GP:
-	 */
-	xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xfeatures_mask_all;
+	if (!use_xsave())
+		return fpu_kernel_cfg.default_size;
+
+	/* XSAVE(S) just needs the legacy and the xstate header part */
+	return sizeof(init_fpstate.regs.xsave);
 }
 
-static inline void fpstate_init_fxstate(struct fxregs_state *fx)
+static inline void fpstate_init_fxstate(struct fpstate *fpstate)
 {
-	fx->cwd = 0x37f;
-	fx->mxcsr = MXCSR_DEFAULT;
+	fpstate->regs.fxsave.cwd = 0x37f;
+	fpstate->regs.fxsave.mxcsr = MXCSR_DEFAULT;
 }
 
 /*
  * Legacy x87 fpstate state init:
  */
-static inline void fpstate_init_fstate(struct fregs_state *fp)
+static inline void fpstate_init_fstate(struct fpstate *fpstate)
 {
-	fp->cwd = 0xffff037fu;
-	fp->swd = 0xffff0000u;
-	fp->twd = 0xffffffffu;
-	fp->fos = 0xffff0000u;
+	fpstate->regs.fsave.cwd = 0xffff037fu;
+	fpstate->regs.fsave.swd = 0xffff0000u;
+	fpstate->regs.fsave.twd = 0xffffffffu;
+	fpstate->regs.fsave.fos = 0xffff0000u;
 }
 
-void fpstate_init(union fpregs_state *state)
+/*
+ * Used in two places:
+ * 1) Early boot to setup init_fpstate for non XSAVE systems
+ * 2) fpu_init_fpstate_user() which is invoked from KVM
+ */
+void fpstate_init_user(struct fpstate *fpstate)
 {
-	if (!static_cpu_has(X86_FEATURE_FPU)) {
-		fpstate_init_soft(&state->soft);
+	if (!cpu_feature_enabled(X86_FEATURE_FPU)) {
+		fpstate_init_soft(&fpstate->regs.soft);
 		return;
 	}
 
-	memset(state, 0, fpu_kernel_xstate_size);
+	xstate_init_xcomp_bv(&fpstate->regs.xsave, fpstate->xfeatures);
 
-	if (static_cpu_has(X86_FEATURE_XSAVES))
-		fpstate_init_xstate(&state->xsave);
-	if (static_cpu_has(X86_FEATURE_FXSR))
-		fpstate_init_fxstate(&state->fxsave);
+	if (cpu_feature_enabled(X86_FEATURE_FXSR))
+		fpstate_init_fxstate(fpstate);
 	else
-		fpstate_init_fstate(&state->fsave);
+		fpstate_init_fstate(fpstate);
+}
+
+static void __fpstate_reset(struct fpstate *fpstate)
+{
+	/* Initialize sizes and feature masks */
+	fpstate->size		= fpu_kernel_cfg.default_size;
+	fpstate->user_size	= fpu_user_cfg.default_size;
+	fpstate->xfeatures	= fpu_kernel_cfg.default_features;
+	fpstate->user_xfeatures	= fpu_user_cfg.default_features;
+	fpstate->xfd		= init_fpstate.xfd;
+}
+
+void fpstate_reset(struct fpu *fpu)
+{
+	/* Set the fpstate pointer to the default fpstate */
+	fpu->fpstate = &fpu->__fpstate;
+	__fpstate_reset(fpu->fpstate);
+
+	/* Initialize the permission related info in fpu */
+	fpu->perm.__state_perm		= fpu_kernel_cfg.default_features;
+	fpu->perm.__state_size		= fpu_kernel_cfg.default_size;
+	fpu->perm.__user_state_size	= fpu_user_cfg.default_size;
+}
+
+static inline void fpu_inherit_perms(struct fpu *dst_fpu)
+{
+	if (fpu_state_size_dynamic()) {
+		struct fpu *src_fpu = &current->group_leader->thread.fpu;
+
+		spin_lock_irq(&current->sighand->siglock);
+		/* Fork also inherits the permissions of the parent */
+		dst_fpu->perm = src_fpu->perm;
+		spin_unlock_irq(&current->sighand->siglock);
+	}
 }
-EXPORT_SYMBOL_GPL(fpstate_init);
 
 /* Clone current's FPU state on fork */
-int fpu_clone(struct task_struct *dst)
+int fpu_clone(struct task_struct *dst, unsigned long clone_flags)
 {
 	struct fpu *src_fpu = &current->thread.fpu;
 	struct fpu *dst_fpu = &dst->thread.fpu;
@@ -256,30 +473,51 @@ int fpu_clone(struct task_struct *dst)
 	/* The new task's FPU state cannot be valid in the hardware. */
 	dst_fpu->last_cpu = -1;
 
+	fpstate_reset(dst_fpu);
+
 	if (!cpu_feature_enabled(X86_FEATURE_FPU))
 		return 0;
 
 	/*
-	 * Don't let 'init optimized' areas of the XSAVE area
-	 * leak into the child task:
+	 * Enforce reload for user space tasks and prevent kernel threads
+	 * from trying to save the FPU registers on context switch.
+	 */
+	set_tsk_thread_flag(dst, TIF_NEED_FPU_LOAD);
+
+	/*
+	 * No FPU state inheritance for kernel threads and IO
+	 * worker threads.
+	 */
+	if (dst->flags & (PF_KTHREAD | PF_IO_WORKER)) {
+		/* Clear out the minimal state */
+		memcpy(&dst_fpu->fpstate->regs, &init_fpstate.regs,
+		       init_fpstate_copy_size());
+		return 0;
+	}
+
+	/*
+	 * If a new feature is added, ensure all dynamic features are
+	 * caller-saved from here!
 	 */
-	memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size);
+	BUILD_BUG_ON(XFEATURE_MASK_USER_DYNAMIC != XFEATURE_MASK_XTILE_DATA);
 
 	/*
-	 * If the FPU registers are not owned by current just memcpy() the
-	 * state.  Otherwise save the FPU registers directly into the
-	 * child's FPU context, without any memory-to-memory copying.
+	 * Save the default portion of the current FPU state into the
+	 * clone. Assume all dynamic features to be defined as caller-
+	 * saved, which enables skipping both the expansion of fpstate
+	 * and the copying of any dynamic state.
+	 *
+	 * Do not use memcpy() when TIF_NEED_FPU_LOAD is set because
+	 * copying is not valid when current uses non-default states.
 	 */
 	fpregs_lock();
 	if (test_thread_flag(TIF_NEED_FPU_LOAD))
-		memcpy(&dst_fpu->state, &src_fpu->state, fpu_kernel_xstate_size);
-
-	else
-		save_fpregs_to_fpstate(dst_fpu);
+		fpregs_restore_userregs();
+	save_fpregs_to_fpstate(dst_fpu);
+	if (!(clone_flags & CLONE_THREAD))
+		fpu_inherit_perms(dst_fpu);
 	fpregs_unlock();
 
-	set_tsk_thread_flag(dst, TIF_NEED_FPU_LOAD);
-
 	trace_x86_fpu_copy_src(src_fpu);
 	trace_x86_fpu_copy_dst(dst_fpu);
 
@@ -287,6 +525,16 @@ int fpu_clone(struct task_struct *dst)
 }
 
 /*
+ * Whitelist the FPU register state embedded into task_struct for hardened
+ * usercopy.
+ */
+void fpu_thread_struct_whitelist(unsigned long *offset, unsigned long *size)
+{
+	*offset = offsetof(struct thread_struct, fpu.__fpstate.regs);
+	*size = fpu_kernel_cfg.default_size;
+}
+
+/*
  * Drops current FPU state: deactivates the fpregs and
  * the fpstate. NOTE: it still leaves previous contents
  * in the fpregs in the eager-FPU case.
@@ -319,28 +567,19 @@ void fpu__drop(struct fpu *fpu)
 static inline void restore_fpregs_from_init_fpstate(u64 features_mask)
 {
 	if (use_xsave())
-		os_xrstor(&init_fpstate.xsave, features_mask);
+		os_xrstor(&init_fpstate, features_mask);
 	else if (use_fxsr())
-		fxrstor(&init_fpstate.fxsave);
+		fxrstor(&init_fpstate.regs.fxsave);
 	else
-		frstor(&init_fpstate.fsave);
+		frstor(&init_fpstate.regs.fsave);
 
 	pkru_write_default();
 }
 
-static inline unsigned int init_fpstate_copy_size(void)
-{
-	if (!use_xsave())
-		return fpu_kernel_xstate_size;
-
-	/* XSAVE(S) just needs the legacy and the xstate header part */
-	return sizeof(init_fpstate.xsave);
-}
-
 /*
  * Reset current->fpu memory state to the init values.
  */
-static void fpu_reset_fpstate(void)
+static void fpu_reset_fpregs(void)
 {
 	struct fpu *fpu = &current->thread.fpu;
 
@@ -359,7 +598,7 @@ static void fpu_reset_fpstate(void)
 	 * user space as PKRU is eagerly written in switch_to() and
 	 * flush_thread().
 	 */
-	memcpy(&fpu->state, &init_fpstate, init_fpstate_copy_size());
+	memcpy(&fpu->fpstate->regs, &init_fpstate.regs, init_fpstate_copy_size());
 	set_thread_flag(TIF_NEED_FPU_LOAD);
 	fpregs_unlock();
 }
@@ -375,7 +614,7 @@ void fpu__clear_user_states(struct fpu *fpu)
 
 	fpregs_lock();
 	if (!cpu_feature_enabled(X86_FEATURE_FPU)) {
-		fpu_reset_fpstate();
+		fpu_reset_fpregs();
 		fpregs_unlock();
 		return;
 	}
@@ -385,12 +624,11 @@ void fpu__clear_user_states(struct fpu *fpu)
 	 * corresponding registers.
 	 */
 	if (xfeatures_mask_supervisor() &&
-	    !fpregs_state_valid(fpu, smp_processor_id())) {
-		os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor());
-	}
+	    !fpregs_state_valid(fpu, smp_processor_id()))
+		os_xrstor_supervisor(fpu->fpstate);
 
 	/* Reset user states in registers. */
-	restore_fpregs_from_init_fpstate(xfeatures_mask_restore_user());
+	restore_fpregs_from_init_fpstate(XFEATURE_MASK_USER_RESTORE);
 
 	/*
 	 * Now all FPU registers have their desired values.  Inform the FPU
@@ -405,7 +643,8 @@ void fpu__clear_user_states(struct fpu *fpu)
 
 void fpu_flush_thread(void)
 {
-	fpu_reset_fpstate();
+	fpstate_reset(&current->thread.fpu);
+	fpu_reset_fpregs();
 }
 /*
  * Load FPU context before returning to userspace.
@@ -445,7 +684,6 @@ void fpregs_mark_activate(void)
 	fpu->last_cpu = smp_processor_id();
 	clear_thread_flag(TIF_NEED_FPU_LOAD);
 }
-EXPORT_SYMBOL_GPL(fpregs_mark_activate);
 
 /*
  * x87 math exception handling:
@@ -468,11 +706,11 @@ int fpu__exception_code(struct fpu *fpu, int trap_nr)
 		 * fully reproduce the context of the exception.
 		 */
 		if (boot_cpu_has(X86_FEATURE_FXSR)) {
-			cwd = fpu->state.fxsave.cwd;
-			swd = fpu->state.fxsave.swd;
+			cwd = fpu->fpstate->regs.fxsave.cwd;
+			swd = fpu->fpstate->regs.fxsave.swd;
 		} else {
-			cwd = (unsigned short)fpu->state.fsave.cwd;
-			swd = (unsigned short)fpu->state.fsave.swd;
+			cwd = (unsigned short)fpu->fpstate->regs.fsave.cwd;
+			swd = (unsigned short)fpu->fpstate->regs.fsave.swd;
 		}
 
 		err = swd & ~cwd;
@@ -486,7 +724,7 @@ int fpu__exception_code(struct fpu *fpu, int trap_nr)
 		unsigned short mxcsr = MXCSR_DEFAULT;
 
 		if (boot_cpu_has(X86_FEATURE_XMM))
-			mxcsr = fpu->state.fxsave.mxcsr;
+			mxcsr = fpu->fpstate->regs.fxsave.mxcsr;
 
 		err = ~(mxcsr >> 7) & mxcsr;
 	}