[PATCH 02/10] arm64: KVM: Add invalidate_icache_range helper

Marc Zyngier
2017-10-09T15:20:24Z

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.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/cacheflush.h | 8 ++++++++
arch/arm64/include/asm/kvm_mmu.h | 4 ++--
arch/arm64/mm/cache.S | 24 ++++++++++++++++++++++++
3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 76d1cc85d5b1..ad56406944c6 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -52,6 +52,13 @@
* - start - virtual start address
* - end - virtual end address
*
+ * invalidate_icache_range(start, end)
+ *
+ * Invalidate the I-cache in the region described by start, end.
+ * Linear mapping only!
+ * - 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 +73,7 @@
* - size - region size
*/
extern void flush_icache_range(unsigned long start, unsigned long end);
+extern void 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 4c4cb4f0e34f..48d31ca2ce9c 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -250,8 +250,8 @@ static inline void __coherent_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);
}
}

diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index 7f1dbe962cf5..0c330666a8c9 100644
--- a/arch/arm64/mm/cache.S
+++ b/arch/arm64/mm/cache.S
@@ -80,6 +80,30 @@ USER(9f, ic ivau, x4 ) // invalidate I line PoU
ENDPROC(flush_icache_range)
ENDPROC(__flush_cache_user_range)

+/*
+ * invalidate_icache_range(start,end)
+ *
+ * Ensure that the I cache is invalid within specified region. This
+ * assumes that this is done on the linear mapping. Do not use it
+ * on a userspace range, as this may fault horribly.
+ *
+ * - start - virtual start address of region
+ * - end - virtual end address of region
+ */
+ENTRY(invalidate_icache_range)
+ icache_line_size x2, x3
+ sub x3, x2, #1
+ bic x4, x0, x3
+1:
+ ic ivau, x4 // invalidate I line PoU
+ add x4, x4, x2
+ cmp x4, x1
+ b.lo 1b
+ dsb ish
+ isb
+ ret
+ENDPROC(invalidate_icache_range)
+
/*
* __flush_dcache_area(kaddr, size)
*
--
2.14.1