target/arm: Move helper_dc_zva to helper-a64.c

This is an aarch64-only function.  Move it out of the shared file.
This patch is code movement only.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200302175829.2183-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 91 insertions, 0 deletions

diff --git a/target/arm/helper-a64.c b/target/arm/helper-a64.c
index 123ce50e7a..bc0649a44a 100644
--- a/target/arm/helper-a64.c
+++ b/target/arm/helper-a64.c
@@ -18,6 +18,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "cpu.h"
 #include "exec/gdbstub.h"
 #include "exec/helper-proto.h"
@@ -1109,4 +1110,94 @@ uint32_t HELPER(sqrt_f16)(uint32_t a, void *fpstp)
     return float16_sqrt(a, s);
 }
 
+void HELPER(dc_zva)(CPUARMState *env, uint64_t vaddr_in)
+{
+    /*
+     * Implement DC ZVA, which zeroes a fixed-length block of memory.
+     * Note that we do not implement the (architecturally mandated)
+     * alignment fault for attempts to use this on Device memory
+     * (which matches the usual QEMU behaviour of not implementing either
+     * alignment faults or any memory attribute handling).
+     */
 
+    ARMCPU *cpu = env_archcpu(env);
+    uint64_t blocklen = 4 << cpu->dcz_blocksize;
+    uint64_t vaddr = vaddr_in & ~(blocklen - 1);
+
+#ifndef CONFIG_USER_ONLY
+    {
+        /*
+         * Slightly awkwardly, QEMU's TARGET_PAGE_SIZE may be less than
+         * the block size so we might have to do more than one TLB lookup.
+         * We know that in fact for any v8 CPU the page size is at least 4K
+         * and the block size must be 2K or less, but TARGET_PAGE_SIZE is only
+         * 1K as an artefact of legacy v5 subpage support being present in the
+         * same QEMU executable. So in practice the hostaddr[] array has
+         * two entries, given the current setting of TARGET_PAGE_BITS_MIN.
+         */
+        int maxidx = DIV_ROUND_UP(blocklen, TARGET_PAGE_SIZE);
+        void *hostaddr[DIV_ROUND_UP(2 * KiB, 1 << TARGET_PAGE_BITS_MIN)];
+        int try, i;
+        unsigned mmu_idx = cpu_mmu_index(env, false);
+        TCGMemOpIdx oi = make_memop_idx(MO_UB, mmu_idx);
+
+        assert(maxidx <= ARRAY_SIZE(hostaddr));
+
+        for (try = 0; try < 2; try++) {
+
+            for (i = 0; i < maxidx; i++) {
+                hostaddr[i] = tlb_vaddr_to_host(env,
+                                                vaddr + TARGET_PAGE_SIZE * i,
+                                                1, mmu_idx);
+                if (!hostaddr[i]) {
+                    break;
+                }
+            }
+            if (i == maxidx) {
+                /*
+                 * If it's all in the TLB it's fair game for just writing to;
+                 * we know we don't need to update dirty status, etc.
+                 */
+                for (i = 0; i < maxidx - 1; i++) {
+                    memset(hostaddr[i], 0, TARGET_PAGE_SIZE);
+                }
+                memset(hostaddr[i], 0, blocklen - (i * TARGET_PAGE_SIZE));
+                return;
+            }
+            /*
+             * OK, try a store and see if we can populate the tlb. This
+             * might cause an exception if the memory isn't writable,
+             * in which case we will longjmp out of here. We must for
+             * this purpose use the actual register value passed to us
+             * so that we get the fault address right.
+             */
+            helper_ret_stb_mmu(env, vaddr_in, 0, oi, GETPC());
+            /* Now we can populate the other TLB entries, if any */
+            for (i = 0; i < maxidx; i++) {
+                uint64_t va = vaddr + TARGET_PAGE_SIZE * i;
+                if (va != (vaddr_in & TARGET_PAGE_MASK)) {
+                    helper_ret_stb_mmu(env, va, 0, oi, GETPC());
+                }
+            }
+        }
+
+        /*
+         * Slow path (probably attempt to do this to an I/O device or
+         * similar, or clearing of a block of code we have translations
+         * cached for). Just do a series of byte writes as the architecture
+         * demands. It's not worth trying to use a cpu_physical_memory_map(),
+         * memset(), unmap() sequence here because:
+         *  + we'd need to account for the blocksize being larger than a page
+         *  + the direct-RAM access case is almost always going to be dealt
+         *    with in the fastpath code above, so there's no speed benefit
+         *  + we would have to deal with the map returning NULL because the
+         *    bounce buffer was in use
+         */
+        for (i = 0; i < blocklen; i++) {
+            helper_ret_stb_mmu(env, vaddr + i, 0, oi, GETPC());
+        }
+    }
+#else
+    memset(g2h(vaddr), 0, blocklen);
+#endif
+}