KVM: arm64: Reserve memory for host stage 2

Extend the memory pool allocated for the hypervisor to include enough
pages to map all of memory at page granularity for the host stage 2.
While at it, also reserve some memory for device mappings.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-27-qperret@google.com

arch/arm64/kvm/hyp/include/nvhe/mm.h

@@ -53,7 +53,7 @@ static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
 	return total;
 }
 
-static inline unsigned long hyp_s1_pgtable_pages(void)
+static inline unsigned long __hyp_pgtable_total_pages(void)
 {
 	unsigned long res = 0, i;
 
@@ -63,9 +63,34 @@ static inline unsigned long hyp_s1_pgtable_pages(void)
 		res += __hyp_pgtable_max_pages(reg->size >> PAGE_SHIFT);
 	}
 
+	return res;
+}
+
+static inline unsigned long hyp_s1_pgtable_pages(void)
+{
+	unsigned long res;
+
+	res = __hyp_pgtable_total_pages();
+
 	/* Allow 1 GiB for private mappings */
 	res += __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
 
 	return res;
 }
+
+static inline unsigned long host_s2_mem_pgtable_pages(void)
+{
+	/*
+	 * Include an extra 16 pages to safely upper-bound the worst case of
+	 * concatenated pgds.
+	 */
+	return __hyp_pgtable_total_pages() + 16;
+}
+
+static inline unsigned long host_s2_dev_pgtable_pages(void)
+{
+	/* Allow 1 GiB for MMIO mappings */
+	return __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
+}
+
 #endif /* __KVM_HYP_MM_H */

arch/arm64/kvm/hyp/nvhe/setup.c

@@ -24,6 +24,8 @@ unsigned long hyp_nr_cpus;
 
 static void *vmemmap_base;
 static void *hyp_pgt_base;
+static void *host_s2_mem_pgt_base;
+static void *host_s2_dev_pgt_base;
 
 static int divide_memory_pool(void *virt, unsigned long size)
 {
@@ -42,6 +44,16 @@ static int divide_memory_pool(void *virt, unsigned long size)
 	if (!hyp_pgt_base)
 		return -ENOMEM;
 
+	nr_pages = host_s2_mem_pgtable_pages();
+	host_s2_mem_pgt_base = hyp_early_alloc_contig(nr_pages);
+	if (!host_s2_mem_pgt_base)
+		return -ENOMEM;
+
+	nr_pages = host_s2_dev_pgtable_pages();
+	host_s2_dev_pgt_base = hyp_early_alloc_contig(nr_pages);
+	if (!host_s2_dev_pgt_base)
+		return -ENOMEM;
+
 	return 0;
 }
 

arch/arm64/kvm/hyp/reserved_mem.c

@@ -52,6 +52,8 @@ void __init kvm_hyp_reserve(void)
 	}
 
 	hyp_mem_pages += hyp_s1_pgtable_pages();
+	hyp_mem_pages += host_s2_mem_pgtable_pages();
+	hyp_mem_pages += host_s2_dev_pgtable_pages();
 
 	/*
 	 * The hyp_vmemmap needs to be backed by pages, but these pages