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>

4 files changed, 52 insertions, 12 deletions

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index aef72d886677..0884e1fdfd30 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 955130762a3c..bef9f418f089 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 8034b96fb3a4..56b3e03c85e7 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);
         }
 }
 
diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index 7f1dbe962cf5..bedd23da83f4 100644
--- a/arch/arm64/mm/cache.S
+++ b/arch/arm64/mm/cache.S
@@ -60,16 +60,7 @@ user_alt 9f, "dc cvau, x4",  "dc civac, x4",  ARM64_WORKAROUND_CLEAN_CACHE
         b.lo    1b
         dsb     ish
 
-        icache_line_size x2, x3
-        sub     x3, x2, #1
-        bic     x4, x0, x3
-1:
-USER(9f, ic     ivau, x4        )               // invalidate I line PoU
-        add     x4, x4, x2
-        cmp     x4, x1
-        b.lo    1b
-        dsb     ish
-        isb
+        invalidate_icache_by_line x0, x1, x2, x3, 9f
         mov     x0, #0
 1:
         uaccess_ttbr0_disable x1
@@ -81,6 +72,27 @@ ENDPROC(flush_icache_range)
 ENDPROC(__flush_cache_user_range)
 
 /*
+ *      invalidate_icache_range(start,end)
+ *
+ *      Ensure that the I cache is invalid within specified region.
+ *
+ *      - start   - virtual start address of region
+ *      - end     - virtual end address of region
+ */
+ENTRY(invalidate_icache_range)
+        uaccess_ttbr0_enable x2, x3
+
+        invalidate_icache_by_line x0, x1, x2, x3, 2f
+        mov     x0, xzr
+1:
+        uaccess_ttbr0_disable x1
+        ret
+2:
+        mov     x0, #-EFAULT
+        b       1b
+ENDPROC(invalidate_icache_range)
+
+/*
  *      __flush_dcache_area(kaddr, size)
  *
  *      Ensure that any D-cache lines for the interval [kaddr, kaddr+size)