On 2016年11月04日 01:03, Paolo Bonzini wrote:
On 03/11/2016 10:27, Jason Wang wrote:
This patch introduces a helper to query the iotlb entry for a
possible iova. This will be used by later device IOTLB API to enable
the capability for a dataplane (e.g vhost) to query the IOTLB.
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Peter Crosthwaite <crosthwaite.pe...@gmail.com>
Cc: Richard Henderson <r...@twiddle.net>
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
exec.c | 33 +++++++++++++++++++++++++++++++++
include/exec/memory.h | 6 ++++++
2 files changed, 39 insertions(+)
diff --git a/exec.c b/exec.c
index b1094c0..00c7a2b 100644
--- a/exec.c
+++ b/exec.c
@@ -449,6 +449,39 @@ 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)
+{
+ IOMMUTLBEntry iotlb = {0};
+ MemoryRegionSection *section;
+ MemoryRegion *mr;
+ hwaddr plen;
plen must be initialized on entry to address_space_translate_internal,
since it's set to
MIN(plen, MIN(section->size,
addr - section->offset_within_address_space))
after address_space_translate_internal calls
address_space_lookup_region. But you don't really need plen, so you
should do this:
section = address_space_lookup_region(d, addr, false);
addr = addr
- section->offset_within_address_space
+ section->offset_within_region;
instead of
section = address_space_translate_internal(d, addr, &addr,
&plen, true);
and then you don't even need a plen anymore.
Cool, will do this in next version.
Also:
+ for (;;) {
+ AddressSpaceDispatch *d = atomic_rcu_read(&as->dispatch);
+ section = address_space_translate_internal(d, addr, &addr, &plen,
true);
+ mr = section->mr;
+
+ if (!mr->iommu_ops) {
+ break;
+ }
+
+ iotlb = mr->iommu_ops->translate(mr, addr, is_write);
+ addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
+ | (addr & iotlb.addr_mask));
This addr assignment is only needed after the iotlb.perm check, so move
it there.
Thanks,
Paolo
Right.
Thanks
+ plen = MIN(plen, (addr | iotlb.addr_mask) - addr + 1);
+ if (!(iotlb.perm & (1 << is_write))) {
+ iotlb.target_as = NULL;
+ break;
+ }
+
+ as = iotlb.target_as;
+ }
+
+ return iotlb;
+}
+
+/* Called from RCU critical section */
MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr,
hwaddr *xlat, hwaddr *plen,
bool is_write)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 9728a2f..e605de3 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1404,6 +1404,12 @@ void address_space_stq_le(AddressSpace *as, hwaddr addr,
uint64_t val,
void address_space_stq_be(AddressSpace *as, hwaddr addr, uint64_t val,
MemTxAttrs attrs, MemTxResult *result);
+/* address_space_get_iotlb_entry: translate an address into an IOTLB
+ * entry. Should be called from an RCU critical section.
+ */
+IOMMUTLBEntry address_space_get_iotlb_entry(AddressSpace *as, hwaddr addr,
+ bool is_write);
+
/* address_space_translate: translate an address range into an address space
* into a MemoryRegion and an address range into that section. Should be
* called from an RCU critical section, to avoid that the last reference
