arm/arm64: KVM: Always have merged page tables

We're in a position where we can now always have "merged" page
tables, where both the runtime mapping and the idmap coexist.

This results in some code being removed, but there is more to come.

Signed-off-by: Marc Zyngier <[e-mail]>
Signed-off-by: Christoffer Dall <[e-mail]>

arch/arm/kvm/mmu.c

···
 
 	if (boot_hyp_pgd) {
 		unmap_hyp_range(boot_hyp_pgd, hyp_idmap_start, PAGE_SIZE);
-		unmap_hyp_range(boot_hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
 		free_pages((unsigned long)boot_hyp_pgd, hyp_pgd_order);
 		boot_hyp_pgd = NULL;
 	}
 
 	if (hyp_pgd)
-		unmap_hyp_range(hyp_pgd, TRAMPOLINE_VA, PAGE_SIZE);
+		unmap_hyp_range(hyp_pgd, hyp_idmap_start, PAGE_SIZE);
 
 	mutex_unlock(&kvm_hyp_pgd_mutex);
 }
···
 	if (__kvm_cpu_uses_extended_idmap())
 		return virt_to_phys(merged_hyp_pgd);
 	else
-		return virt_to_phys(boot_hyp_pgd);
+		return virt_to_phys(hyp_pgd);
 }
 
 phys_addr_t kvm_get_idmap_vector(void)
···
 phys_addr_t kvm_get_idmap_start(void)
 {
 	return hyp_idmap_start;
+}
+
+static int kvm_map_idmap_text(pgd_t *pgd)
+{
+	int err;
+
+	/* Create the idmap in the boot page tables */
+	err = 	__create_hyp_mappings(pgd,
+				      hyp_idmap_start, hyp_idmap_end,
+				      __phys_to_pfn(hyp_idmap_start),
+				      PAGE_HYP_EXEC);
+	if (err)
+		kvm_err("Failed to idmap %lx-%lx\n",
+			hyp_idmap_start, hyp_idmap_end);
+
+	return err;
 }
 
 int kvm_mmu_init(void)
···
 	BUG_ON((hyp_idmap_start ^ (hyp_idmap_end - 1)) & PAGE_MASK);
 
 	hyp_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, hyp_pgd_order);
-	boot_hyp_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, hyp_pgd_order);
-
-	if (!hyp_pgd || !boot_hyp_pgd) {
+	if (!hyp_pgd) {
 		kvm_err("Hyp mode PGD not allocated\n");
 		err = -ENOMEM;
 		goto out;
 	}
 
-	/* Create the idmap in the boot page tables */
-	err = 	__create_hyp_mappings(boot_hyp_pgd,
-				      hyp_idmap_start, hyp_idmap_end,
-				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP_EXEC);
-
-	if (err) {
-		kvm_err("Failed to idmap %lx-%lx\n",
-			hyp_idmap_start, hyp_idmap_end);
-		goto out;
-	}
-
 	if (__kvm_cpu_uses_extended_idmap()) {
+		boot_hyp_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+							 hyp_pgd_order);
+		if (!boot_hyp_pgd) {
+			kvm_err("Hyp boot PGD not allocated\n");
+			err = -ENOMEM;
+			goto out;
+		}
+
+		err = kvm_map_idmap_text(boot_hyp_pgd);
+		if (err)
+			goto out;
+
 		merged_hyp_pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
 		if (!merged_hyp_pgd) {
 			kvm_err("Failed to allocate extra HYP pgd\n");
···
 		}
 		__kvm_extend_hypmap(boot_hyp_pgd, hyp_pgd, merged_hyp_pgd,
 				    hyp_idmap_start);
-		return 0;
-	}
-
-	/* Map the very same page at the trampoline VA */
-	err = 	__create_hyp_mappings(boot_hyp_pgd,
-				      TRAMPOLINE_VA, TRAMPOLINE_VA + PAGE_SIZE,
-				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP_EXEC);
-	if (err) {
-		kvm_err("Failed to map trampoline @%lx into boot HYP pgd\n",
-			TRAMPOLINE_VA);
-		goto out;
-	}
-
-	/* Map the same page again into the runtime page tables */
-	err = 	__create_hyp_mappings(hyp_pgd,
-				      TRAMPOLINE_VA, TRAMPOLINE_VA + PAGE_SIZE,
-				      __phys_to_pfn(hyp_idmap_start),
-				      PAGE_HYP_EXEC);
-	if (err) {
-		kvm_err("Failed to map trampoline @%lx into runtime HYP pgd\n",
-			TRAMPOLINE_VA);
-		goto out;
+	} else {
+		err = kvm_map_idmap_text(hyp_pgd);
+		if (err)
+			goto out;
 	}
 
 	return 0;

arch/arm64/kvm/reset.c

···
 	return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);
 }
 
-extern char __hyp_idmap_text_start[];
-
 unsigned long kvm_hyp_reset_entry(void)
 {
-	if (!__kvm_cpu_uses_extended_idmap()) {
-		unsigned long offset;
-
-		/*
-		 * Find the address of __kvm_hyp_reset() in the trampoline page.
-		 * This is present in the running page tables, and the boot page
-		 * tables, so we call the code here to start the trampoline
-		 * dance in reverse.
-		 */
-		offset = (unsigned long)__kvm_hyp_reset
-			 - ((unsigned long)__hyp_idmap_text_start & PAGE_MASK);
-
-		return TRAMPOLINE_VA + offset;
-	} else {
-		/*
-		 * KVM is running with merged page tables, which don't have the
-		 * trampoline page mapped. We know the idmap is still mapped,
-		 * but can't be called into directly. Use
-		 * __extended_idmap_trampoline to do the call.
-		 */
-		return (unsigned long)kvm_ksym_ref(__extended_idmap_trampoline);
-	}
+	/*
+	 * KVM is running with merged page tables, which don't have the
+	 * trampoline page mapped. We know the idmap is still mapped,
+	 * but can't be called into directly. Use
+	 * __extended_idmap_trampoline to do the call.
+	 */
+	return (unsigned long)kvm_ksym_ref(__extended_idmap_trampoline);
 }