Subject: Re: [RFC PATCH 15/27] of/fdt: Introduce early_init_dt_add_memory_hyp()

From: Quentin Perret <[email-masked]>
Date: Wed, 18 Nov 2020 14:31:42 +0000

On Wednesday 18 Nov 2020 at 09:25:47 (+0000), Quentin Perret wrote:
> I'll have a go at the memblock stuff to see if I find a way to make it
> work from that angle.

OK, no luck with the memblock API, but I figured that I can actually
postpone the KVM memory reservation to a later point, after
unflatten_device_tree(), which lets me iterate over the memory nodes
directly rather than having the fdt driver do it for me.

The below seems to boot alright (though I'm not too familiar with
of_address_to_resource() so I may not be using right) and keeps the
whole thing in arch/arm64. Thoughts?

Thanks,
Quentin

---8<---
diff --git a/arch/arm64/kvm/hyp/reserved_mem.c b/arch/arm64/kvm/hyp/reserved_mem.c
index 7da8e2915c1c..cab5ad587a3a 100644
--- a/arch/arm64/kvm/hyp/reserved_mem.c
+++ b/arch/arm64/kvm/hyp/reserved_mem.c
@@ -6,6 +6,7 @@
 
 #include <linux/kvm_host.h>
 #include <linux/memblock.h>
+#include <linux/of_address.h>
 #include <linux/sort.h>
 
 #include <asm/kvm_host.h>
@@ -16,7 +17,7 @@
 phys_addr_t hyp_mem_base;
 phys_addr_t hyp_mem_size;
 
-void __init early_init_dt_add_memory_hyp(u64 base, u64 size)
+static int __init add_hyp_memblock_region(struct resource *rsrc)
 {
 	struct hyp_memblock_region *reg;
 
@@ -24,12 +25,14 @@ void __init early_init_dt_add_memory_hyp(u64 base, u64 size)
 		kvm_nvhe_sym(hyp_memblock_nr) = -1;
 
 	if (kvm_nvhe_sym(hyp_memblock_nr) < 0)
-		return;
+		return -ENOMEM;
 
 	reg = kvm_nvhe_sym(hyp_memory);
-	reg[kvm_nvhe_sym(hyp_memblock_nr)].start = base;
-	reg[kvm_nvhe_sym(hyp_memblock_nr)].end = base + size;
+	reg[kvm_nvhe_sym(hyp_memblock_nr)].start = rsrc->start;
+	reg[kvm_nvhe_sym(hyp_memblock_nr)].end = rsrc->end;
 	kvm_nvhe_sym(hyp_memblock_nr)++;
+
+	return 0;
 }
 
 static int cmp_hyp_memblock(const void *p1, const void *p2)
@@ -52,7 +55,10 @@ void kvm_sort_memblock_regions(void)
 extern bool enable_protected_kvm;
 void __init reserve_kvm_hyp(void)
 {
+	struct device_node *np;
+	struct resource rsrc;
 	u64 nr_pages, prev;
+	int i;
 
 	if (!enable_protected_kvm)
 		return;
@@ -60,8 +66,14 @@ void __init reserve_kvm_hyp(void)
 	if (!is_hyp_mode_available() || is_kernel_in_hyp_mode())
 		return;
 
-	if (kvm_nvhe_sym(hyp_memblock_nr) <= 0)
-		return;
+	for_each_node_by_type(np, "memory") {
+		for (i = 0; !of_address_to_resource(np, i, &rsrc); i++) {
+			if (!add_hyp_memblock_region(&rsrc))
+				continue;
+			kvm_err("Failed to add hyp memblock\n");
+			return;
+		}
+	}
 
 	hyp_mem_size += num_possible_cpus() << PAGE_SHIFT;
 	hyp_mem_size += hyp_s1_pgtable_size();
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index f81da019b677..114f788a4da4 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -391,7 +391,6 @@ void __init arm64_memblock_init(void)
 
 	reserve_elfcorehdr();
 
-	reserve_kvm_hyp();
 
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 
@@ -423,6 +422,8 @@ void __init bootmem_init(void)
 
 	dma_pernuma_cma_reserve();
 
+	reserve_kvm_hyp();
+
 	/*
 	 * sparse_init() tries to allocate memory from memblock, so must be
 	 * done after the fixed reservations
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index af2b5a09c5b4..4602e467ca8b 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1099,10 +1099,6 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 #define MAX_MEMBLOCK_ADDR	((phys_addr_t)~0)
 #endif
 
-void __init __weak early_init_dt_add_memory_hyp(u64 base, u64 size)
-{
-}
-
 void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 {
 	const u64 phys_offset = MIN_MEMBLOCK_ADDR;
@@ -1143,7 +1139,6 @@ void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
 		base = phys_offset;
 	}
 	memblock_add(base, size);
-	early_init_dt_add_memory_hyp(base, size);
 }
 
 int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size)

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