[Xen-devel] [PATCH] xen/arm: flush icache as well when XEN_DOMCTL_cacheflush is issued

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

When the toolstack modifies memory of a running ARM VM it may happen
that the underlying memory of a current vCPU PC is changed. Without
flushing the icache the vCPU may continue executing stale instructions.

In this patch we introduce VA-based icache flushing macros. Also expose
the xc_domain_cacheflush through xenctrl.h.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>

Note: patch has been verified to solve stale icache issues on the
      HiKey platform.
---
 tools/libxc/include/xenctrl.h    |  6 ++++++
 tools/libxc/xc_private.h         |  3 ---
 xen/arch/arm/mm.c                |  1 +
 xen/include/asm-arm/arm32/page.h |  3 +++
 xen/include/asm-arm/arm64/page.h |  3 +++
 xen/include/asm-arm/page.h       | 31 +++++++++++++++++++++++++++++++
 6 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 63c616ff6a..cb80a2b07c 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2720,6 +2720,12 @@ int xc_livepatch_revert(xc_interface *xch, char *name, 
uint32_t timeout);
 int xc_livepatch_unload(xc_interface *xch, char *name, uint32_t timeout);
 int xc_livepatch_replace(xc_interface *xch, char *name, uint32_t timeout);
 
+/*
+ * ARM only. Ensure cache coherency after memory modifications.
+ */
+int xc_domain_cacheflush(xc_interface *xch, uint32_t domid,
+                         xen_pfn_t start_pfn, xen_pfn_t nr_pfns);
+
 /* Compat shims */
 #include "xenctrl_compat.h"
 
diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
index 97445ae1fe..fddebdc917 100644
--- a/tools/libxc/xc_private.h
+++ b/tools/libxc/xc_private.h
@@ -366,9 +366,6 @@ void bitmap_byte_to_64(uint64_t *lp, const uint8_t *bp, int 
nbits);
 /* Optionally flush file to disk and discard page cache */
 void discard_file_cache(xc_interface *xch, int fd, int flush);
 
-int xc_domain_cacheflush(xc_interface *xch, uint32_t domid,
-                        xen_pfn_t start_pfn, xen_pfn_t nr_pfns);
-
 #define MAX_MMU_UPDATES 1024
 struct xc_mmu {
     mmu_update_t updates[MAX_MMU_UPDATES];
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 99588a330d..43e5b3d9e2 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -389,6 +389,7 @@ void flush_page_to_ram(unsigned long mfn)
     void *v = map_domain_page(_mfn(mfn));
 
     clean_and_invalidate_dcache_va_range(v, PAGE_SIZE);
+    invalidate_icache_va_range(v, PAGE_SIZE);
     unmap_domain_page(v);
 }
 
diff --git a/xen/include/asm-arm/arm32/page.h b/xen/include/asm-arm/arm32/page.h
index ea4b312c70..10e5288d0f 100644
--- a/xen/include/asm-arm/arm32/page.h
+++ b/xen/include/asm-arm/arm32/page.h
@@ -19,6 +19,9 @@ static inline void write_pte(lpae_t *p, lpae_t pte)
         : : "r" (pte.bits), "r" (p) : "memory");
 }
 
+/* Inline ASM to invalidate icache on register R (may be an inline asm 
operand) */
+#define __invalidate_icache_one(R) STORE_CP32(R, ICIMVAU)
+
 /* Inline ASM to invalidate dcache on register R (may be an inline asm 
operand) */
 #define __invalidate_dcache_one(R) STORE_CP32(R, DCIMVAC)
 
diff --git a/xen/include/asm-arm/arm64/page.h b/xen/include/asm-arm/arm64/page.h
index 23d778154d..0f380b95b4 100644
--- a/xen/include/asm-arm/arm64/page.h
+++ b/xen/include/asm-arm/arm64/page.h
@@ -16,6 +16,9 @@ static inline void write_pte(lpae_t *p, lpae_t pte)
         : : "r" (pte.bits), "r" (p) : "memory");
 }
 
+/* Inline ASM to invalidate icache on register R (may be an inline asm 
operand) */
+#define __invalidate_icache_one(R) "ic ivau, %" #R ";"
+
 /* Inline ASM to invalidate dcache on register R (may be an inline asm 
operand) */
 #define __invalidate_dcache_one(R) "dc ivac, %" #R ";"
 
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index c492d6df50..a618d0e556 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -371,6 +371,37 @@ static inline int clean_and_invalidate_dcache_va_range
             : : "r" (_p), "m" (*_p));                                   \
 } while (0)
 
+static inline int invalidate_icache_va_range(const void *p, unsigned long size)
+{
+    size_t off;
+    const void *end = p + size;
+
+    dsb(sy);           /* So the CPU issues all writes to the range */
+
+    off = (unsigned long)p % cacheline_bytes;
+    if ( off )
+    {
+        p -= off;
+        asm volatile (__invalidate_icache_one(0) : : "r" (p));
+        p += cacheline_bytes;
+        size -= cacheline_bytes - off;
+    }
+    off = (unsigned long)end % cacheline_bytes;
+    if ( off )
+    {
+        end -= off;
+        size -= off;
+        asm volatile (__invalidate_icache_one(0) : : "r" (end));
+    }
+
+    for ( ; p < end; p += cacheline_bytes )
+        asm volatile (__invalidate_icache_one(0) : : "r" (p));
+
+    dsb(sy);           /* So we know the flushes happen before continuing */
+
+    return 0;
+}
+
 /*
  * Flush a range of VA's hypervisor mappings from the data TLB of the
  * local processor. This is not sufficient when changing code mappings
-- 
2.11.0


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