arm64: KVM: Avoid marking pages as XN in Stage-2 if CTR_EL0.DIC is set

On systems where CTR_EL0.DIC is set, we don't need to perform
icache invalidation to guarantee that we'll fetch the right
instruction stream.

This also means that taking a permission fault to invalidate the
icache is an unnecessary overhead.

On such systems, we can safely leave the page as being executable.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index c66c3047400e8ce8d2cb9738d2205e8c590ff6d2..78b942c1bea437c5a0e9124b86afd4c48503d999 100644 (file)
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -77,8 +77,18 @@
                __val;                                                  \
         })
 
-#define PAGE_S2                        __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(NORMAL) | PTE_S2_RDONLY | PTE_S2_XN)
-#define PAGE_S2_DEVICE         __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(DEVICE_nGnRE) | PTE_S2_RDONLY | PTE_S2_XN)
+#define PAGE_S2_XN                                                     \
+       ({                                                              \
+               u64 __val;                                              \
+               if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC))           \
+                       __val = 0;                                      \
+               else                                                    \
+                       __val = PTE_S2_XN;                              \
+               __val;                                                  \
+       })
+
+#define PAGE_S2                        __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(NORMAL) | PTE_S2_RDONLY | PAGE_S2_XN)
+#define PAGE_S2_DEVICE         __pgprot(_PROT_DEFAULT | PAGE_S2_MEMATTR(DEVICE_nGnRE) | PTE_S2_RDONLY | PAGE_S2_XN)
 
 #define PAGE_NONE              __pgprot(((_PAGE_DEFAULT) & ~PTE_VALID) | PTE_PROT_NONE | PTE_RDONLY | PTE_NG | PTE_PXN | PTE_UXN)
 #define PAGE_SHARED            __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE)