}
#if IS_ENABLED(CONFIG_KVM)
-static void __fpstate_reset(struct fpstate *fpstate);
+static void __fpstate_reset(struct fpstate *fpstate, u64 xfd);
+
+static void fpu_init_guest_permissions(struct fpu_guest *gfpu)
+{
+ struct fpu_state_perm *fpuperm;
+ u64 perm;
+
+ if (!IS_ENABLED(CONFIG_X86_64))
+ return;
+
+ spin_lock_irq(¤t->sighand->siglock);
+ fpuperm = ¤t->group_leader->thread.fpu.guest_perm;
+ perm = fpuperm->__state_perm;
+
+ /* First fpstate allocation locks down permissions. */
+ WRITE_ONCE(fpuperm->__state_perm, perm | FPU_GUEST_PERM_LOCKED);
+
+ spin_unlock_irq(¤t->sighand->siglock);
+
+ gfpu->perm = perm & ~FPU_GUEST_PERM_LOCKED;
+}
bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu)
{
if (!fpstate)
return false;
- __fpstate_reset(fpstate);
+ /* Leave xfd to 0 (the reset value defined by spec) */
+ __fpstate_reset(fpstate, 0);
fpstate_init_user(fpstate);
fpstate->is_valloc = true;
fpstate->is_guest = true;
- gfpu->fpstate = fpstate;
+ gfpu->fpstate = fpstate;
+ gfpu->xfeatures = fpu_user_cfg.default_features;
+ gfpu->perm = fpu_user_cfg.default_features;
+ gfpu->uabi_size = fpu_user_cfg.default_size;
+ fpu_init_guest_permissions(gfpu);
+
return true;
}
EXPORT_SYMBOL_GPL(fpu_alloc_guest_fpstate);
}
EXPORT_SYMBOL_GPL(fpu_free_guest_fpstate);
+/*
+ * fpu_enable_guest_xfd_features - Check xfeatures against guest perm and enable
+ * @guest_fpu: Pointer to the guest FPU container
+ * @xfeatures: Features requested by guest CPUID
+ *
+ * Enable all dynamic xfeatures according to guest perm and requested CPUID.
+ *
+ * Return: 0 on success, error code otherwise
+ */
+int fpu_enable_guest_xfd_features(struct fpu_guest *guest_fpu, u64 xfeatures)
+{
+ lockdep_assert_preemption_enabled();
+
+ /* Nothing to do if all requested features are already enabled. */
+ xfeatures &= ~guest_fpu->xfeatures;
+ if (!xfeatures)
+ return 0;
+
+ return __xfd_enable_feature(xfeatures, guest_fpu);
+}
+EXPORT_SYMBOL_GPL(fpu_enable_guest_xfd_features);
+
+#ifdef CONFIG_X86_64
+void fpu_update_guest_xfd(struct fpu_guest *guest_fpu, u64 xfd)
+{
+ fpregs_lock();
+ guest_fpu->fpstate->xfd = xfd;
+ if (guest_fpu->fpstate->in_use)
+ xfd_update_state(guest_fpu->fpstate);
+ fpregs_unlock();
+}
+EXPORT_SYMBOL_GPL(fpu_update_guest_xfd);
+
+/**
+ * fpu_sync_guest_vmexit_xfd_state - Synchronize XFD MSR and software state
+ *
+ * Must be invoked from KVM after a VMEXIT before enabling interrupts when
+ * XFD write emulation is disabled. This is required because the guest can
+ * freely modify XFD and the state at VMEXIT is not guaranteed to be the
+ * same as the state on VMENTER. So software state has to be udpated before
+ * any operation which depends on it can take place.
+ *
+ * Note: It can be invoked unconditionally even when write emulation is
+ * enabled for the price of a then pointless MSR read.
+ */
+void fpu_sync_guest_vmexit_xfd_state(void)
+{
+ struct fpstate *fps = current->thread.fpu.fpstate;
+
+ lockdep_assert_irqs_disabled();
+ if (fpu_state_size_dynamic()) {
+ rdmsrl(MSR_IA32_XFD, fps->xfd);
+ __this_cpu_write(xfd_state, fps->xfd);
+ }
+}
+EXPORT_SYMBOL_GPL(fpu_sync_guest_vmexit_xfd_state);
+#endif /* CONFIG_X86_64 */
+
int fpu_swap_kvm_fpstate(struct fpu_guest *guest_fpu, bool enter_guest)
{
struct fpstate *guest_fps = guest_fpu->fpstate;
fpstate_init_fstate(fpstate);
}
-static void __fpstate_reset(struct fpstate *fpstate)
+static void __fpstate_reset(struct fpstate *fpstate, u64 xfd)
{
/* 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;
+ fpstate->xfd = xfd;
}
void fpstate_reset(struct fpu *fpu)
{
/* Set the fpstate pointer to the default fpstate */
fpu->fpstate = &fpu->__fpstate;
- __fpstate_reset(fpu->fpstate);
+ __fpstate_reset(fpu->fpstate, init_fpstate.xfd);
/* 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;
+ /* Same defaults for guests */
+ fpu->guest_perm = fpu->perm;
}
static inline void fpu_inherit_perms(struct fpu *dst_fpu)
spin_lock_irq(¤t->sighand->siglock);
/* Fork also inherits the permissions of the parent */
dst_fpu->perm = src_fpu->perm;
+ dst_fpu->guest_perm = src_fpu->guest_perm;
spin_unlock_irq(¤t->sighand->siglock);
}
}