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

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

Moving to the VGIC implies giving access to some io devices
(the VGIC virtual CPU interface registers) to the guest.

Define kvm_phys_addr_ioremap() to map a device at a guest IPA.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm/include/asm/kvm_mmu.h |    2 ++
 arch/arm/kvm/mmu.c             |   44 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 422ec45..c59ecf9 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -35,6 +35,8 @@ void free_hyp_pmds(void);
 
 int kvm_alloc_stage2_pgd(struct kvm *kvm);
 void kvm_free_stage2_pgd(struct kvm *kvm);
+int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
+			  phys_addr_t pa, unsigned long size);
 
 int kvm_handle_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run);
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index c37afd0..ca76be0 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -244,8 +244,12 @@ static void free_guest_pages(pte_t *pte, unsigned long addr)
 
 	for (i = 0; i < PTRS_PER_PTE; i++) {
 		if (pte_present(*pte)) {
-			page = pfn_to_page(pte_pfn(*pte));
-			put_page(page);
+			unsigned long pfn = pte_pfn(*pte);
+
+			if (pfn_valid(pfn)) { /* Skip over device memory */
+				page = pfn_to_page(pfn);
+				put_page(page);
+			}
 			put_page(pte_page);
 		}
 		pte++;
@@ -471,6 +475,42 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	return ret;
 }
 
+/*
+ * kvm_phys_addr_ioremap -- Map a device range to guest IPA
+ *
+ * @kvm:	The KVM pointer
+ * @guest_ipa:	The IPA at which to insert the mapping
+ * @pa:		The physical address of the device
+ * @size:	The size of the mapping
+ */
+int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
+			  phys_addr_t pa, unsigned long size)
+{
+	phys_addr_t addr, end;
+	pgprot_t prot;
+	int ret = 0;
+	unsigned long pfn;
+
+	end = (guest_ipa + size + PAGE_SIZE - 1) & PAGE_MASK;
+	prot = __pgprot(get_mem_type_prot_pte(MT_DEVICE) | L_PTE_USER |
+			L_PTE2_READ | L_PTE2_WRITE);
+	pfn = __phys_to_pfn(pa);
+
+	spin_lock(&kvm->arch.pgd_lock);
+	for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
+		pte_t pte = pfn_pte(pfn, prot);
+
+		ret = stage2_set_pte(kvm, addr, &pte);
+		if (ret)
+			break;
+
+		pfn++;
+	}
+	spin_unlock(&kvm->arch.pgd_lock);
+
+	return ret;
+}
+
 /**
  * kvm_handle_mmio_return -- Handle MMIO loads after user space emulation
  * @vcpu: The VCPU pointer
-- 
1.7.10.3