arm64: KVM: Add invalidate_icache_range helper

We currently tightly couple dcache clean with icache invalidation,
but KVM could do without the initial flush to PoU, as we've
already flushed things to PoC.

Let's introduce invalidate_icache_range which is limited to
invalidating the icache from the linear mapping (and thus
has none of the userspace fault handling complexity), and
wire it in KVM instead of flush_icache_range.

Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

3 files changed, 30 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index aef72d8..0884e1f 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -388,6 +388,27 @@ alternative_endif
 	.endm
 
 /*
+ * Macro to perform an instruction cache maintenance for the interval
+ * [start, end)
+ *
+ * 	start, end:	virtual addresses describing the region
+ *	label:		A label to branch to on user fault.
+ * 	Corrupts:	tmp1, tmp2
+ */
+	.macro invalidate_icache_by_line start, end, tmp1, tmp2, label
+	icache_line_size \tmp1, \tmp2
+	sub	\tmp2, \tmp1, #1
+	bic	\tmp2, \start, \tmp2
+9997:
+USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
+	add	\tmp2, \tmp2, \tmp1
+	cmp	\tmp2, \end
+	b.lo	9997b
+	dsb	ish
+	isb
+	.endm
+
+/*
  * reset_pmuserenr_el0 - reset PMUSERENR_EL0 if PMUv3 present
  */
 	.macro	reset_pmuserenr_el0, tmpreg
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 9551307..bef9f41 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -52,6 +52,12 @@
  *		- start  - virtual start address
  *		- end    - virtual end address
  *
+ *	invalidate_icache_range(start, end)
+ *
+ *		Invalidate the I-cache in the region described by start, end.
+ *		- start  - virtual start address
+ *		- end    - virtual end address
+ *
  *	__flush_cache_user_range(start, end)
  *
  *		Ensure coherency between the I-cache and the D-cache in the
@@ -66,6 +72,7 @@
  *		- size   - region size
  */
 extern void flush_icache_range(unsigned long start, unsigned long end);
+extern int  invalidate_icache_range(unsigned long start, unsigned long end);
 extern void __flush_dcache_area(void *addr, size_t len);
 extern void __inval_dcache_area(void *addr, size_t len);
 extern void __clean_dcache_area_poc(void *addr, size_t len);
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 8034b96..56b3e03 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -250,8 +250,8 @@ static inline void __invalidate_icache_guest_page(struct kvm_vcpu *vcpu,
 		/* PIPT or VPIPT at EL2 (see comment in __kvm_tlb_flush_vmid_ipa) */
 		void *va = page_address(pfn_to_page(pfn));
 
-		flush_icache_range((unsigned long)va,
-				   (unsigned long)va + size);
+		invalidate_icache_range((unsigned long)va,
+					(unsigned long)va + size);
 	}
 }