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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 06/17] x86/hvm: revert 82ed8716b "fix direct PCI port I/O emulation retry...
...and error handling"
NOTE: A straight reversion was not possible because of subsequent changes
in the code so this at least partially a manual reversion.
By limiting hvmemul_do_io_addr() to reps falling within the pages on which
a reference has already been taken, we can guarantee that calls to
hvm_copy_to/from_guest_phys() will not hit the HVMCOPY_gfn_paged_out
or HVMCOPY_gfn_shared cases. Thus we can remove the retry logic from
the intercept code and simplify it significantly.
Normally hvmemul_do_io_addr() will only reference single page at a time.
It will, however, take an extra page reference for I/O spanning a page
boundary.
It is still important to know, upon returning from x86_emulate(), whether
the number of reps was reduced so the mmio_retry flag is retained for that
purpose but renamed to io_retry (since it's applicable to port I/O as well
as memory mapped I/O).
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 81 +++++++++++++++++++++++++++-------------
xen/arch/x86/hvm/intercept.c | 56 ++++++---------------------
xen/include/asm-x86/hvm/vcpu.h | 2 +-
3 files changed, 68 insertions(+), 71 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 33e0242..47da5b9 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -60,6 +60,7 @@ static int hvmemul_do_io(
.type = is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO,
.addr = addr,
.size = size,
+ .count = *reps,
.dir = dir,
.df = df,
.data = data,
@@ -134,15 +135,6 @@ static int hvmemul_do_io(
HVMIO_dispatched : HVMIO_awaiting_completion;
vio->io_size = size;
- /*
- * When retrying a repeated string instruction, force exit to guest after
- * completion of the retried iteration to allow handling of interrupts.
- */
- if ( vio->mmio_retrying )
- *reps = 1;
-
- p.count = *reps;
-
if ( dir == IOREQ_WRITE )
{
if ( !data_is_addr )
@@ -156,17 +148,9 @@ static int hvmemul_do_io(
switch ( rc )
{
case X86EMUL_OKAY:
- case X86EMUL_RETRY:
- *reps = p.count;
p.state = STATE_IORESP_READY;
- if ( !vio->mmio_retry )
- {
- hvm_io_assist(&p);
- vio->io_state = HVMIO_none;
- }
- else
- /* Defer hvm_io_assist() invocation to hvm_do_resume(). */
- vio->io_state = HVMIO_handle_mmio_awaiting_completion;
+ hvm_io_assist(&p);
+ vio->io_state = HVMIO_none;
break;
case X86EMUL_UNHANDLEABLE:
{
@@ -289,17 +273,64 @@ int hvmemul_do_io_addr(
bool_t is_mmio, paddr_t addr, unsigned long *reps, unsigned int size,
uint8_t dir, bool_t df, paddr_t ram_addr)
{
- struct page_info *ram_page;
+ struct vcpu *v = current;
+ unsigned long ram_gmfn = paddr_to_pfn(ram_addr);
+ struct page_info *ram_page[2];
+ int nr_pages = 0;
+ unsigned long count;
int rc;
- rc = hvmemul_acquire_page(paddr_to_pfn(ram_addr), &ram_page);
+ rc = hvmemul_acquire_page(ram_gmfn, &ram_page[nr_pages]);
if ( rc != X86EMUL_OKAY )
- return rc;
+ goto out;
+
+ nr_pages++;
+
+ /* Detemine how many reps will fit within this page */
+ for ( count = 0; count < *reps; count++ )
+ {
+ paddr_t start, end;
+
+ if ( df )
+ {
+ start = ram_addr - count * size;
+ end = ram_addr + size - 1;
+ }
+ else
+ {
+ start = ram_addr;
+ end = ram_addr + (count + 1) * size - 1;
+ }
+
+ if ( paddr_to_pfn(start) != ram_gmfn ||
+ paddr_to_pfn(end) != ram_gmfn )
+ break;
+ }
+
+ if ( count == 0 )
+ {
+ /*
+ * This access must span two pages, so grab a reference to
+ * the next page and do a single rep.
+ */
+ rc = hvmemul_acquire_page(df ? ram_gmfn - 1 : ram_gmfn + 1,
+ &ram_page[nr_pages]);
+ if ( rc != X86EMUL_OKAY )
+ goto out;
+
+ nr_pages++;
+ count = 1;
+ }
+
+ v->arch.hvm_vcpu.hvm_io.io_retry = (count < *reps);
+ *reps = count;
rc = hvmemul_do_io(is_mmio, addr, reps, size, dir, df, 1,
(uint64_t)ram_addr);
- hvmemul_release_page(ram_page);
+ out:
+ while ( --nr_pages >= 0 )
+ hvmemul_release_page(ram_page[nr_pages]);
return rc;
}
@@ -1547,8 +1578,6 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt
*hvmemul_ctxt,
}
hvmemul_ctxt->exn_pending = 0;
- vio->mmio_retrying = vio->mmio_retry;
- vio->mmio_retry = 0;
if ( cpu_has_vmx )
hvmemul_ctxt->ctxt.swint_emulate = x86_swint_emulate_none;
@@ -1559,7 +1588,7 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt
*hvmemul_ctxt,
rc = x86_emulate(&hvmemul_ctxt->ctxt, ops);
- if ( rc == X86EMUL_OKAY && vio->mmio_retry )
+ if ( rc == X86EMUL_OKAY && vio->io_retry )
rc = X86EMUL_RETRY;
if ( rc != X86EMUL_RETRY )
{
diff --git a/xen/arch/x86/hvm/intercept.c b/xen/arch/x86/hvm/intercept.c
index 3c85756..d10682b 100644
--- a/xen/arch/x86/hvm/intercept.c
+++ b/xen/arch/x86/hvm/intercept.c
@@ -155,7 +155,6 @@ static const struct hvm_io_ops portio_ops = {
static int process_io_intercept(struct vcpu *v, ioreq_t *p,
struct hvm_io_handler *handler)
{
- struct hvm_vcpu_io *vio = &v->arch.hvm_vcpu.hvm_io;
const struct hvm_io_ops *ops = handler->ops;
int rc = X86EMUL_OKAY, i, step = p->df ? -p->size : p->size;
uint64_t data;
@@ -165,58 +164,38 @@ static int process_io_intercept(struct vcpu *v, ioreq_t
*p,
{
for ( i = 0; i < p->count; i++ )
{
- if ( vio->mmio_retrying )
- {
- if ( vio->mmio_large_read_bytes != p->size )
- return X86EMUL_UNHANDLEABLE;
- memcpy(&data, vio->mmio_large_read, p->size);
- vio->mmio_large_read_bytes = 0;
- vio->mmio_retrying = 0;
- }
- else
- {
- addr = (p->type == IOREQ_TYPE_COPY) ?
- p->addr + step * i :
- p->addr;
- rc = ops->read(handler, v, addr, p->size, &data);
- if ( rc != X86EMUL_OKAY )
- break;
- }
+ addr = (p->type == IOREQ_TYPE_COPY) ?
+ p->addr + step * i :
+ p->addr;
+ rc = ops->read(handler, v, addr, p->size, &data);
+ if ( rc != X86EMUL_OKAY )
+ break;
if ( p->data_is_ptr )
{
switch ( hvm_copy_to_guest_phys(p->data + step * i,
- &data, p->size) )
+ &data, p->size) )
{
case HVMCOPY_okay:
break;
- case HVMCOPY_gfn_paged_out:
- case HVMCOPY_gfn_shared:
- rc = X86EMUL_RETRY;
- break;
case HVMCOPY_bad_gfn_to_mfn:
/* Drop the write as real hardware would. */
continue;
case HVMCOPY_bad_gva_to_gfn:
+ case HVMCOPY_gfn_paged_out:
+ case HVMCOPY_gfn_shared:
ASSERT(0);
/* fall through */
default:
rc = X86EMUL_UNHANDLEABLE;
break;
}
- if ( rc != X86EMUL_OKAY)
+ if ( rc != X86EMUL_OKAY )
break;
}
else
p->data = data;
}
-
- if ( rc == X86EMUL_RETRY )
- {
- vio->mmio_retry = 1;
- vio->mmio_large_read_bytes = p->size;
- memcpy(vio->mmio_large_read, &data, p->size);
- }
}
else /* p->dir == IOREQ_WRITE */
{
@@ -229,14 +208,12 @@ static int process_io_intercept(struct vcpu *v, ioreq_t
*p,
{
case HVMCOPY_okay:
break;
- case HVMCOPY_gfn_paged_out:
- case HVMCOPY_gfn_shared:
- rc = X86EMUL_RETRY;
- break;
case HVMCOPY_bad_gfn_to_mfn:
data = ~0;
break;
case HVMCOPY_bad_gva_to_gfn:
+ case HVMCOPY_gfn_paged_out:
+ case HVMCOPY_gfn_shared:
ASSERT(0);
/* fall through */
default:
@@ -256,15 +233,6 @@ static int process_io_intercept(struct vcpu *v, ioreq_t *p,
if ( rc != X86EMUL_OKAY )
break;
}
-
- if ( rc == X86EMUL_RETRY )
- vio->mmio_retry = 1;
- }
-
- if ( i != 0 )
- {
- p->count = i;
- rc = X86EMUL_OKAY;
}
return rc;
diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h
index dd08416..9ecb702 100644
--- a/xen/include/asm-x86/hvm/vcpu.h
+++ b/xen/include/asm-x86/hvm/vcpu.h
@@ -74,7 +74,7 @@ struct hvm_vcpu_io {
* For string instruction emulation we need to be able to signal a
* necessary retry through other than function return codes.
*/
- bool_t mmio_retry, mmio_retrying;
+ bool_t io_retry;
unsigned long msix_unmask_address;
--
1.7.10.4
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