[Android-virt] [PATCH 4/6] ARM: KVM: Add support for IO mapping at the HYP level

[marc.zyngier at arm.com (Marc Zyngier)]

Moving to the VGIC implies giving access to some ioremapped
devices (the VGIC virtual interface control registers) to the
hypervisor.

Define create_hyp_io_mappings() as the IO aware sibling of
create_hyp_mappings(), and extend the mapping functions
to support a pte mapping backend.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm/include/asm/kvm_mmu.h |    1 +
 arch/arm/kvm/mmu.c             |   46 +++++++++++++++++++++++++++++++++++----
 2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 917edd7..eb05401 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -31,6 +31,7 @@ extern pgd_t *kvm_hyp_pgd;
 extern struct mutex kvm_hyp_pgd_mutex;
 
 int create_hyp_mappings(pgd_t *hyp_pgd, void *from, void *to);
+int create_hyp_io_mappings(pgd_t *hyp_pgd, void *from, void *to, phys_addr_t);
 void free_hyp_pmds(pgd_t *hyp_pgd);
 
 int kvm_alloc_stage2_pgd(struct kvm *kvm);
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 8375aed..5c809b8 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -16,11 +16,13 @@
 
 #include <linux/mman.h>
 #include <linux/kvm_host.h>
+#include <linux/io.h>
 #include <trace/events/kvm.h>
 #include <asm/pgalloc.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_emulate.h>
+#include <asm/mach/map.h>
 
 #include "trace.h"
 
@@ -72,8 +74,10 @@ void free_hyp_pmds(pgd_t *hyp_pgd)
 	mutex_unlock(&kvm_hyp_pgd_mutex);
 }
 
+typedef void (*hyp_pte_map_fn_t)(pmd_t *, unsigned long, unsigned long, unsigned long *);
+
 static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start,
-						unsigned long end)
+				    unsigned long end, unsigned long *pfn_base)
 {
 	pte_t *pte;
 	struct page *page;
@@ -88,8 +92,27 @@ static void create_hyp_pte_mappings(pmd_t *pmd, unsigned long start,
 	}
 }
 
+static void create_hyp_pte_io_mappings(pmd_t *pmd, unsigned long start,
+				       unsigned long end, unsigned long *pfn_base)
+{
+	pte_t *pte;
+	unsigned long addr;
+	pgprot_t prot;
+
+	prot = __pgprot(get_mem_type_prot_pte(MT_DEVICE) | L_PTE_USER);
+
+	for (addr = start & PAGE_MASK; addr < end; addr += PAGE_SIZE) {
+		BUG_ON(pfn_valid(*pfn_base));
+		pte = pte_offset_kernel(pmd, addr);
+
+		set_pte_ext(pte, pfn_pte(*pfn_base, prot), 0);
+		(*pfn_base)++;
+	}
+}
+
 static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
-					       unsigned long end)
+				   unsigned long end, hyp_pte_map_fn_t map_fn,
+				   unsigned long *pfn_base)
 {
 	pmd_t *pmd;
 	pte_t *pte;
@@ -110,7 +133,7 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
 		}
 
 		next = pmd_addr_end(addr, end);
-		create_hyp_pte_mappings(pmd, addr, next);
+		map_fn(pmd, addr, next, pfn_base);
 	}
 
 	return 0;
@@ -127,7 +150,9 @@ static int create_hyp_pmd_mappings(pud_t *pud, unsigned long start,
  *
  * Note: Wrapping around zero in the "to" address is not supported.
  */
-int create_hyp_mappings(pgd_t *hyp_pgd, void *from, void *to)
+static int __create_hyp_mappings(pgd_t *hyp_pgd, void *from, void *to,
+				 hyp_pte_map_fn_t map_fn,
+				 unsigned long *pfn_base)
 {
 	unsigned long start = (unsigned long)from;
 	unsigned long end = (unsigned long)to;
@@ -157,7 +182,7 @@ int create_hyp_mappings(pgd_t *hyp_pgd, void *from, void *to)
 		}
 
 		next = pgd_addr_end(addr, end);
-		err = create_hyp_pmd_mappings(pud, addr, next);
+		err = create_hyp_pmd_mappings(pud, addr, next, map_fn, pfn_base);
 		if (err)
 			goto out;
 	}
@@ -166,6 +191,17 @@ out:
 	return err;
 }
 
+int create_hyp_mappings(pgd_t *hyp_pgd, void *from, void *to)
+{
+	return __create_hyp_mappings(hyp_pgd, from, to, create_hyp_pte_mappings, NULL);
+}
+
+int create_hyp_io_mappings(pgd_t *hyp_pgd, void *from, void *to, phys_addr_t addr)
+{
+	unsigned long pfn = __phys_to_pfn(addr);
+	return __create_hyp_mappings(hyp_pgd, from, to, create_hyp_pte_io_mappings, &pfn);
+}
+
 /**
  * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
  * @kvm:	The KVM struct pointer for the VM.
-- 
1.7.7.1