arm64: KVM: Implement TLB handling

Implement the TLB handling as a direct translation of the assembly
code version.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm64/kvm/hyp/Makefile

@@ -10,3 +10,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += debug-sr.o
 obj-$(CONFIG_KVM_ARM_HOST) += entry.o
 obj-$(CONFIG_KVM_ARM_HOST) += switch.o
 obj-$(CONFIG_KVM_ARM_HOST) += fpsimd.o
+obj-$(CONFIG_KVM_ARM_HOST) += tlb.o

arch/arm64/kvm/hyp/entry.S

@@ -147,6 +147,7 @@ ENTRY(__fpsimd_guest_restore)
 	add	x0, x2, #CPU_GP_REG_OFFSET(CPU_FP_REGS)
 	bl	__fpsimd_restore_state
 
+	// Skip restoring fpexc32 for AArch64 guests
 	mrs	x1, hcr_el2
 	tbnz	x1, #HCR_RW_SHIFT, 1f
 	ldr	x4, [x2, #CPU_SYSREG_OFFSET(FPEXC32_EL2)]

arch/arm64/kvm/hyp/tlb.c

+/*
+ * Copyright (C) 2015 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyngier@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hyp.h"
+
+void __hyp_text __tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
+{
+	dsb(ishst);
+
+	/* Switch to requested VMID */
+	kvm = kern_hyp_va(kvm);
+	write_sysreg(kvm->arch.vttbr, vttbr_el2);
+	isb();
+
+	/*
+	 * We could do so much better if we had the VA as well.
+	 * Instead, we invalidate Stage-2 for this IPA, and the
+	 * whole of Stage-1. Weep...
+	 */
+	ipa >>= 12;
+	asm volatile("tlbi ipas2e1is, %0" : : "r" (ipa));
+
+	/*
+	 * We have to ensure completion of the invalidation at Stage-2,
+	 * since a table walk on another CPU could refill a TLB with a
+	 * complete (S1 + S2) walk based on the old Stage-2 mapping if
+	 * the Stage-1 invalidation happened first.
+	 */
+	dsb(ish);
+	asm volatile("tlbi vmalle1is" : : );
+	dsb(ish);
+	isb();
+
+	write_sysreg(0, vttbr_el2);
+}
+
+void __hyp_text __tlb_flush_vmid(struct kvm *kvm)
+{
+	dsb(ishst);
+
+	/* Switch to requested VMID */
+	kvm = kern_hyp_va(kvm);
+	write_sysreg(kvm->arch.vttbr, vttbr_el2);
+	isb();
+
+	asm volatile("tlbi vmalls12e1is" : : );
+	dsb(ish);
+	isb();
+
+	write_sysreg(0, vttbr_el2);
+}
+
+void __hyp_text __tlb_flush_vm_context(void)
+{
+	dsb(ishst);
+	asm volatile("tlbi alle1is	\n"
+		     "ic ialluis	  ": : );
+	dsb(ish);
+}