From a764040cc831cfe5b8bf1c80e8341b9bf2de3ce8 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Wed, 17 May 2017 16:57:42 +0800
Subject: exec: abstract address_space_do_translate()

This function is an abstraction helper for address_space_translate() and
address_space_get_iotlb_entry(). It does the lookup of address into
memory region section, then does proper IOMMU translation if necessary.
Refactor the two existing functions to use it.

This fixes vhost when IOMMU is disabled by guest.

Tested-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 exec.c | 103 +++++++++++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 69 insertions(+), 34 deletions(-)

(limited to 'exec.c')

diff --git a/exec.c b/exec.c
index eac6085..f942eb2 100644
--- a/exec.c
+++ b/exec.c
@@ -463,18 +463,20 @@ address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *x
 }
 
 /* Called from RCU critical section */
-IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
-                                            bool is_write)
+static MemoryRegionSection address_space_do_translate(AddressSpace *as,
+                                                      hwaddr addr,
+                                                      hwaddr *xlat,
+                                                      hwaddr *plen,
+                                                      bool is_write,
+                                                      bool is_mmio)
 {
-    IOMMUTLBEntry iotlb = {0};
+    IOMMUTLBEntry iotlb;
     MemoryRegionSection *section;
     MemoryRegion *mr;
 
     for (;;) {
         AddressSpaceDispatch *d = atomic_rcu_read(&as->dispatch);
-        section = address_space_lookup_region(d, addr, false);
-        addr = addr - section->offset_within_address_space
-               + section->offset_within_region;
+        section = address_space_translate_internal(d, addr, &addr, plen, is_mmio);
         mr = section->mr;
 
         if (!mr->iommu_ops) {
@@ -482,55 +484,88 @@ IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
         }
 
         iotlb = mr->iommu_ops->translate(mr, addr, is_write);
+        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
+                | (addr & iotlb.addr_mask));
+        *plen = MIN(*plen, (addr | iotlb.addr_mask) - addr + 1);
         if (!(iotlb.perm & (1 << is_write))) {
-            iotlb.target_as = NULL;
-            break;
+            goto translate_fail;
         }
 
-        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
-                | (addr & iotlb.addr_mask));
         as = iotlb.target_as;
     }
 
-    return iotlb;
+    *xlat = addr;
+
+    return *section;
+
+translate_fail:
+    return (MemoryRegionSection) { .mr = &io_mem_unassigned };
 }
 
 /* Called from RCU critical section */
-MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
-                                      hwaddr *xlat, hwaddr *plen,
-                                      bool is_write)
+IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
+                                            bool is_write)
 {
-    IOMMUTLBEntry iotlb;
-    MemoryRegionSection *section;
-    MemoryRegion *mr;
+    MemoryRegionSection section;
+    hwaddr xlat, plen;
 
-    for (;;) {
-        AddressSpaceDispatch *d = atomic_rcu_read(&as->dispatch);
-        section = address_space_translate_internal(d, addr, &addr, plen, true);
-        mr = section->mr;
+    /* Try to get maximum page mask during translation. */
+    plen = (hwaddr)-1;
 
-        if (!mr->iommu_ops) {
-            break;
-        }
+    /* This can never be MMIO. */
+    section = address_space_do_translate(as, addr, &xlat, &plen,
+                                         is_write, false);
 
-        iotlb = mr->iommu_ops->translate(mr, addr, is_write);
-        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
-                | (addr & iotlb.addr_mask));
-        *plen = MIN(*plen, (addr | iotlb.addr_mask) - addr + 1);
-        if (!(iotlb.perm & (1 << is_write))) {
-            mr = &io_mem_unassigned;
-            break;
-        }
+    /* Illegal translation */
+    if (section.mr == &io_mem_unassigned) {
+        goto iotlb_fail;
+    }
 
-        as = iotlb.target_as;
+    /* Convert memory region offset into address space offset */
+    xlat += section.offset_within_address_space -
+        section.offset_within_region;
+
+    if (plen == (hwaddr)-1) {
+        /*
+         * We use default page size here. Logically it only happens
+         * for identity mappings.
+         */
+        plen = TARGET_PAGE_SIZE;
     }
 
+    /* Convert to address mask */
+    plen -= 1;
+
+    return (IOMMUTLBEntry) {
+        .target_as = section.address_space,
+        .iova = addr & ~plen,
+        .translated_addr = xlat & ~plen,
+        .addr_mask = plen,
+        /* IOTLBs are for DMAs, and DMA only allows on RAMs. */
+        .perm = IOMMU_RW,
+    };
+
+iotlb_fail:
+    return (IOMMUTLBEntry) {0};
+}
+
+/* Called from RCU critical section */
+MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
+                                      hwaddr *xlat, hwaddr *plen,
+                                      bool is_write)
+{
+    MemoryRegion *mr;
+    MemoryRegionSection section;
+
+    /* This can be MMIO, so setup MMIO bit. */
+    section = address_space_do_translate(as, addr, xlat, plen, is_write, true);
+    mr = section.mr;
+
     if (xen_enabled() && memory_access_is_direct(mr, is_write)) {
         hwaddr page = ((addr & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE) - addr;
         *plen = MIN(page, *plen);
     }
 
-    *xlat = addr;
     return mr;
 }
 
-- 
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