1 files changed, 111 insertions, 43 deletions

diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 525010504f9d..ec8e4494873d 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -7,14 +7,26 @@
  */
 #include <linux/irqflags.h>
 #include <linux/sched.h>
-#include <linux/thread_info.h>
 #include <linux/kvm_host.h>
 #include <asm/fpsimd.h>
 #include <asm/kvm_asm.h>
-#include <asm/kvm_host.h>
+#include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/sysreg.h>
 
+void kvm_vcpu_unshare_task_fp(struct kvm_vcpu *vcpu)
+{
+	struct task_struct *p = vcpu->arch.parent_task;
+	struct user_fpsimd_state *fpsimd;
+
+	if (!is_protected_kvm_enabled() || !p)
+		return;
+
+	fpsimd = &p->thread.uw.fpsimd_state;
+	kvm_unshare_hyp(fpsimd, fpsimd + 1);
+	put_task_struct(p);
+}
+
 /*
  * Called on entry to KVM_RUN unless this vcpu previously ran at least
  * once and the most recent prior KVM_RUN for this vcpu was called from
@@ -28,25 +40,29 @@ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu)
 {
 	int ret;
 
-	struct thread_info *ti = &current->thread_info;
 	struct user_fpsimd_state *fpsimd = &current->thread.uw.fpsimd_state;
 
-	/*
-	 * Make sure the host task thread flags and fpsimd state are
-	 * visible to hyp:
-	 */
-	ret = create_hyp_mappings(ti, ti + 1, PAGE_HYP);
-	if (ret)
-		goto error;
+	kvm_vcpu_unshare_task_fp(vcpu);
 
-	ret = create_hyp_mappings(fpsimd, fpsimd + 1, PAGE_HYP);
+	/* Make sure the host task fpsimd state is visible to hyp: */
+	ret = kvm_share_hyp(fpsimd, fpsimd + 1);
 	if (ret)
-		goto error;
+		return ret;
 
-	vcpu->arch.host_thread_info = kern_hyp_va(ti);
 	vcpu->arch.host_fpsimd_state = kern_hyp_va(fpsimd);
-error:
-	return ret;
+
+	/*
+	 * We need to keep current's task_struct pinned until its data has been
+	 * unshared with the hypervisor to make sure it is not re-used by the
+	 * kernel and donated to someone else while already shared -- see
+	 * kvm_vcpu_unshare_task_fp() for the matching put_task_struct().
+	 */
+	if (is_protected_kvm_enabled()) {
+		get_task_struct(current);
+		vcpu->arch.parent_task = current;
+	}
+
+	return 0;
 }
 
 /*
@@ -55,40 +71,75 @@ error:
  *
  * Here, we just set the correct metadata to indicate that the FPSIMD
  * state in the cpu regs (if any) belongs to current on the host.
- *
- * TIF_SVE is backed up here, since it may get clobbered with guest state.
- * This flag is restored by kvm_arch_vcpu_put_fp(vcpu).
  */
 void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
 {
 	BUG_ON(!current->mm);
+	BUG_ON(test_thread_flag(TIF_SVE));
 
-	vcpu->arch.flags &= ~(KVM_ARM64_FP_ENABLED |
-			      KVM_ARM64_HOST_SVE_IN_USE |
-			      KVM_ARM64_HOST_SVE_ENABLED);
-	vcpu->arch.flags |= KVM_ARM64_FP_HOST;
+	if (!system_supports_fpsimd())
+		return;
 
-	if (test_thread_flag(TIF_SVE))
-		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_IN_USE;
+	vcpu->arch.fp_state = FP_STATE_HOST_OWNED;
 
+	vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);
 	if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
-		vcpu->arch.flags |= KVM_ARM64_HOST_SVE_ENABLED;
+		vcpu_set_flag(vcpu, HOST_SVE_ENABLED);
+
+	/*
+	 * We don't currently support SME guests but if we leave
+	 * things in streaming mode then when the guest starts running
+	 * FPSIMD or SVE code it may generate SME traps so as a
+	 * special case if we are in streaming mode we force the host
+	 * state to be saved now and exit streaming mode so that we
+	 * don't have to handle any SME traps for valid guest
+	 * operations. Do this for ZA as well for now for simplicity.
+	 */
+	if (system_supports_sme()) {
+		vcpu_clear_flag(vcpu, HOST_SME_ENABLED);
+		if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
+			vcpu_set_flag(vcpu, HOST_SME_ENABLED);
+
+		if (read_sysreg_s(SYS_SVCR) & (SVCR_SM_MASK | SVCR_ZA_MASK)) {
+			vcpu->arch.fp_state = FP_STATE_FREE;
+			fpsimd_save_and_flush_cpu_state();
+		}
+	}
+}
+
+/*
+ * Called just before entering the guest once we are no longer preemptable
+ * and interrupts are disabled. If we have managed to run anything using
+ * FP while we were preemptible (such as off the back of an interrupt),
+ * then neither the host nor the guest own the FP hardware (and it was the
+ * responsibility of the code that used FP to save the existing state).
+ */
+void kvm_arch_vcpu_ctxflush_fp(struct kvm_vcpu *vcpu)
+{
+	if (test_thread_flag(TIF_FOREIGN_FPSTATE))
+		vcpu->arch.fp_state = FP_STATE_FREE;
 }
 
 /*
- * If the guest FPSIMD state was loaded, update the host's context
- * tracking data mark the CPU FPSIMD regs as dirty and belonging to vcpu
- * so that they will be written back if the kernel clobbers them due to
- * kernel-mode NEON before re-entry into the guest.
+ * Called just after exiting the guest. If the guest FPSIMD state
+ * was loaded, update the host's context tracking data mark the CPU
+ * FPSIMD regs as dirty and belonging to vcpu so that they will be
+ * written back if the kernel clobbers them due to kernel-mode NEON
+ * before re-entry into the guest.
  */
 void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
 {
 	WARN_ON_ONCE(!irqs_disabled());
 
-	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
-		fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.gp_regs.fp_regs,
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
+		/*
+		 * Currently we do not support SME guests so SVCR is
+		 * always 0 and we just need a variable to point to.
+		 */
+		fpsimd_bind_state_to_cpu(&vcpu->arch.ctxt.fp_regs,
 					 vcpu->arch.sve_state,
-					 vcpu->arch.sve_max_vl);
+					 vcpu->arch.sve_max_vl,
+					 NULL, 0, &vcpu->arch.svcr);
 
 		clear_thread_flag(TIF_FOREIGN_FPSTATE);
 		update_thread_flag(TIF_SVE, vcpu_has_sve(vcpu));
@@ -104,19 +155,37 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu)
 void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 {
 	unsigned long flags;
-	bool host_has_sve = system_supports_sve();
-	bool guest_has_sve = vcpu_has_sve(vcpu);
 
 	local_irq_save(flags);
 
-	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {
-		u64 *guest_zcr = &vcpu->arch.ctxt.sys_regs[ZCR_EL1];
+	/*
+	 * If we have VHE then the Hyp code will reset CPACR_EL1 to
+	 * CPACR_EL1_DEFAULT and we need to reenable SME.
+	 */
+	if (has_vhe() && system_supports_sme()) {
+		/* Also restore EL0 state seen on entry */
+		if (vcpu_get_flag(vcpu, HOST_SME_ENABLED))
+			sysreg_clear_set(CPACR_EL1, 0,
+					 CPACR_EL1_SMEN_EL0EN |
+					 CPACR_EL1_SMEN_EL1EN);
+		else
+			sysreg_clear_set(CPACR_EL1,
+					 CPACR_EL1_SMEN_EL0EN,
+					 CPACR_EL1_SMEN_EL1EN);
+	}
+
+	if (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED) {
+		if (vcpu_has_sve(vcpu)) {
+			__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);
 
-		fpsimd_save_and_flush_cpu_state();
+			/* Restore the VL that was saved when bound to the CPU */
+			if (!has_vhe())
+				sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,
+						       SYS_ZCR_EL1);
+		}
 
-		if (guest_has_sve)
-			*guest_zcr = read_sysreg_s(SYS_ZCR_EL12);
-	} else if (host_has_sve) {
+		fpsimd_save_and_flush_cpu_state();
+	} else if (has_vhe() && system_supports_sve()) {
 		/*
 		 * The FPSIMD/SVE state in the CPU has not been touched, and we
 		 * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been
@@ -124,14 +193,13 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
 		 * for EL0.  To avoid spurious traps, restore the trap state
 		 * seen by kvm_arch_vcpu_load_fp():
 		 */
-		if (vcpu->arch.flags & KVM_ARM64_HOST_SVE_ENABLED)
+		if (vcpu_get_flag(vcpu, HOST_SVE_ENABLED))
 			sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN);
 		else
 			sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0);
 	}
 
-	update_thread_flag(TIF_SVE,
-			   vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE);
+	update_thread_flag(TIF_SVE, 0);
 
 	local_irq_restore(flags);
 }