[PATCH v3 7/7] ARM: KVM: drop use of PAGE_S2_DEVICE

[Marc Zyngier]

At the moment, when mapping a device into Stage-2 for a guest,
we override whatever the guest uses by forcing a device memory
type in Stage-2.

While this is not exactly wrong, this isn't really the "spirit" of
the architecture. The hardware shouldn't have to cope for a broken
guest mapping to a device as normal memory.

As such, let's get rid of the memory type overrides, and map
everything as PAGE_S2 in Stage-2. This simplifies the code and
let the guest do its own thing, whether it is stupid or not.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm/include/asm/pgtable.h | 2 --
 arch/arm/kvm/mmu.c             | 2 +-
 arch/arm/mm/mmu.c              | 6 ++----
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 9bcd262..c3410a8 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -81,7 +81,6 @@ extern pgprot_t		pgprot_user;
 extern pgprot_t		pgprot_kernel;
 extern pgprot_t		pgprot_hyp_device;
 extern pgprot_t		pgprot_s2;
-extern pgprot_t		pgprot_s2_device;
 
 #define _MOD_PROT(p, b)	__pgprot(pgprot_val(p) | (b))
 
@@ -97,7 +96,6 @@ extern pgprot_t		pgprot_s2_device;
 #define PAGE_HYP		_MOD_PROT(pgprot_kernel, L_PTE_HYP)
 #define PAGE_HYP_DEVICE		_MOD_PROT(pgprot_hyp_device, L_PTE_HYP)
 #define PAGE_S2			_MOD_PROT(pgprot_s2, L_PTE_S2_RDONLY)
-#define PAGE_S2_DEVICE		_MOD_PROT(pgprot_s2_device, L_PTE_USER | L_PTE_S2_RDONLY)
 
 #define __PAGE_NONE		__pgprot(_L_PTE_DEFAULT | L_PTE_RDONLY | L_PTE_XN | L_PTE_NONE)
 #define __PAGE_SHARED		__pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_XN)
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 693d16c..f2a8416 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -495,7 +495,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
 	pfn = __phys_to_pfn(pa);
 
 	for (addr = guest_ipa; addr < end; addr += PAGE_SIZE) {
-		pte_t pte = pfn_pte(pfn, PAGE_S2_DEVICE);
+		pte_t pte = pfn_pte(pfn, PAGE_S2);
 		kvm_set_s2pte_writable(&pte);
 
 		ret = mmu_topup_memory_cache(&cache, 2, 2);
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index e0d8565..bc001f5 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -60,7 +60,6 @@ pgprot_t pgprot_user;
 pgprot_t pgprot_kernel;
 pgprot_t pgprot_hyp_device;
 pgprot_t pgprot_s2;
-pgprot_t pgprot_s2_device;
 
 EXPORT_SYMBOL(pgprot_user);
 EXPORT_SYMBOL(pgprot_kernel);
@@ -343,7 +342,7 @@ static void __init build_mem_type_table(void)
 	struct cachepolicy *cp;
 	unsigned int cr = get_cr();
 	pteval_t user_pgprot, kern_pgprot, vecs_pgprot;
-	pteval_t hyp_device_pgprot, s2_pgprot, s2_device_pgprot;
+	pteval_t hyp_device_pgprot, s2_pgprot;
 	int cpu_arch = cpu_architecture();
 	int i;
 
@@ -456,7 +455,7 @@ static void __init build_mem_type_table(void)
 	cp = &cache_policies[cachepolicy];
 	vecs_pgprot = kern_pgprot = user_pgprot = cp->pte;
 	s2_pgprot = cp->pte_s2;
-	hyp_device_pgprot = s2_device_pgprot = mem_types[MT_DEVICE].prot_pte;
+	hyp_device_pgprot = mem_types[MT_DEVICE].prot_pte;
 
 	/*
 	 * ARMv6 and above have extended page tables.
@@ -536,7 +535,6 @@ static void __init build_mem_type_table(void)
 	pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
 				 L_PTE_DIRTY | kern_pgprot);
 	pgprot_s2  = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | s2_pgprot);
-	pgprot_s2_device  = __pgprot(s2_device_pgprot);
 	pgprot_hyp_device  = __pgprot(hyp_device_pgprot);
 
 	mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
-- 
1.8.2.3