From e85fa0f42359527628b5b2243c514acc9670871a Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 8 Mar 2018 15:58:16 +0100
Subject: [PATCH 03/17] address_space_read: address_space_to_flatview needs RCU
lock
RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20180308155819.20598-4-pbonzini@redhat.com>
Patchwork-id: 79190
O-Subject: [RHEL7.5 qemu-kvm-rhev PATCH 3/6] address_space_read: address_space_to_flatview needs RCU lock
Bugzilla: 1554930
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
address_space_read is calling address_space_to_flatview but it can
be called outside the RCU lock. To fix it, push the rcu_read_lock/unlock
pair up from flatview_read_full to address_space_read's constant size
fast path and address_space_read_full.
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry pick from commit b2a44fcad74f1cc7a6786d38eba7db12ab2352ba)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
exec.c | 38 +++++++++++++++++++++++++-------------
include/exec/memory.h | 23 +++++++++--------------
2 files changed, 34 insertions(+), 27 deletions(-)
diff --git a/exec.c b/exec.c
index 8b50133..43c66da 100644
--- a/exec.c
+++ b/exec.c
@@ -2512,6 +2512,8 @@ static const MemoryRegionOps watch_mem_ops = {
.endianness = DEVICE_NATIVE_ENDIAN,
};
+static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len);
static MemTxResult flatview_write(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
const uint8_t *buf, int len);
static bool flatview_access_valid(FlatView *fv, hwaddr addr, int len,
@@ -3029,24 +3031,18 @@ MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
return result;
}
-MemTxResult flatview_read_full(FlatView *fv, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf, int len)
+/* Called from RCU critical section. */
+static MemTxResult flatview_read(FlatView *fv, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len)
{
hwaddr l;
hwaddr addr1;
MemoryRegion *mr;
- MemTxResult result = MEMTX_OK;
-
- if (len > 0) {
- rcu_read_lock();
- l = len;
- mr = flatview_translate(fv, addr, &addr1, &l, false);
- result = flatview_read_continue(fv, addr, attrs, buf, len,
- addr1, l, mr);
- rcu_read_unlock();
- }
- return result;
+ l = len;
+ mr = flatview_translate(fv, addr, &addr1, &l, false);
+ return flatview_read_continue(fv, addr, attrs, buf, len,
+ addr1, l, mr);
}
static MemTxResult flatview_rw(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
@@ -3067,6 +3063,22 @@ MemTxResult address_space_rw(AddressSpace *as, hwaddr addr,
addr, attrs, buf, len, is_write);
}
+MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len)
+{
+ MemTxResult result = MEMTX_OK;
+ FlatView *fv;
+
+ if (len > 0) {
+ rcu_read_lock();
+ fv = address_space_to_flatview(as);
+ result = flatview_read(fv, addr, attrs, buf, len);
+ rcu_read_unlock();
+ }
+
+ return result;
+}
+
MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
MemTxAttrs attrs,
const uint8_t *buf, int len)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 3df0dcc..a66b6ef 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1917,13 +1917,12 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
/* Internal functions, part of the implementation of address_space_read. */
+MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf, int len);
MemTxResult flatview_read_continue(FlatView *fv, hwaddr addr,
MemTxAttrs attrs, uint8_t *buf,
int len, hwaddr addr1, hwaddr l,
MemoryRegion *mr);
-
-MemTxResult flatview_read_full(FlatView *fv, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf, int len);
void *qemu_map_ram_ptr(RAMBlock *ram_block, ram_addr_t addr);
static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
@@ -1942,7 +1941,7 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
*
* Return a MemTxResult indicating whether the operation succeeded
* or failed (eg unassigned memory, device rejected the transaction,
- * IOMMU fault).
+ * IOMMU fault). Called within RCU critical section.
*
* @as: #AddressSpace to be accessed
* @addr: address within that address space
@@ -1950,17 +1949,20 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
* @buf: buffer with the data transferred
*/
static inline __attribute__((__always_inline__))
-MemTxResult flatview_read(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
- uint8_t *buf, int len)
+MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
+ MemTxAttrs attrs, uint8_t *buf,
+ int len)
{
MemTxResult result = MEMTX_OK;
hwaddr l, addr1;
void *ptr;
MemoryRegion *mr;
+ FlatView *fv;
if (__builtin_constant_p(len)) {
if (len) {
rcu_read_lock();
+ fv = address_space_to_flatview(as);
l = len;
mr = flatview_translate(fv, addr, &addr1, &l, false);
if (len == l && memory_access_is_direct(mr, false)) {
@@ -1973,18 +1975,11 @@ MemTxResult flatview_read(FlatView *fv, hwaddr addr, MemTxAttrs attrs,
rcu_read_unlock();
}
} else {
- result = flatview_read_full(fv, addr, attrs, buf, len);
+ result = address_space_read_full(as, addr, attrs, buf, len);
}
return result;
}
-static inline MemTxResult address_space_read(AddressSpace *as, hwaddr addr,
- MemTxAttrs attrs, uint8_t *buf,
- int len)
-{
- return flatview_read(address_space_to_flatview(as), addr, attrs, buf, len);
-}
-
/**
* address_space_read_cached: read from a cached RAM region
*
--
1.8.3.1