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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/HVM: fix direct PCI port I/O emulation retry and error handling
commit 82ed8716b08ccf2f6239262ecc269c5cd60ef5dd
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Oct 14 09:51:40 2013 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Oct 14 09:51:40 2013 +0200
x86/HVM: fix direct PCI port I/O emulation retry and error handling
dpci_ioport_{read,write}() guest memory access failure handling should
be modelled after process_portio_intercept()'s (and others): Upon
encountering an error on other than the first iteration, the count
successfully handled needs to be stored and X86EMUL_OKAY returned, in
order for the generic instruction emulator to update register state
correctly before reporting failure or retrying (both of which would
only happen after re-invoking emulation).
Further we leverage (and slightly extend, due to the above mentioned
need to return X86EMUL_OKAY) the "large MMIO" retry model.
Note that there is still a special case not explicitly taken care of
here: While the first retry on the last iteration of a "rep ins"
correctly recovers the already read data, an eventual subsequent retry
is being handled by the pre-existing mmio-large logic (through
hvmemul_do_io() storing the [recovered] data [again], also taking into
consideration that the emulator converts a single iteration "ins" to
->read_io() plus ->write()).
Also fix an off-by-one in the mmio-large-read logic, and slightly
simplify the copying of the data.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 26 +++++++++++---
xen/arch/x86/hvm/io.c | 77 +++++++++++++++++++++++++++++++++-------
xen/include/asm-x86/hvm/vcpu.h | 5 +++
3 files changed, 90 insertions(+), 18 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index b206997..15b2257 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -173,6 +173,13 @@ static int hvmemul_do_io(
(p_data == NULL) ? 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->dir = dir;
p->data_is_ptr = value_is_ptr;
p->type = is_mmio ? IOREQ_TYPE_COPY : IOREQ_TYPE_PIO;
@@ -202,8 +209,14 @@ static int hvmemul_do_io(
case X86EMUL_RETRY:
*reps = p->count;
p->state = STATE_IORESP_READY;
- hvm_io_assist();
- vio->io_state = HVMIO_none;
+ if ( !vio->mmio_retry )
+ {
+ hvm_io_assist();
+ vio->io_state = HVMIO_none;
+ }
+ else
+ /* Defer hvm_io_assist() invocation to hvm_do_resume(). */
+ vio->io_state = HVMIO_handle_mmio_awaiting_completion;
break;
case X86EMUL_UNHANDLEABLE:
rc = X86EMUL_RETRY;
@@ -249,10 +262,9 @@ static int hvmemul_do_io(
if ( bytes == 0 )
pa = vio->mmio_large_read_pa = addr;
if ( (addr == (pa + bytes)) &&
- ((bytes + size) <
- sizeof(vio->mmio_large_read)) )
+ ((bytes + size) <= sizeof(vio->mmio_large_read)) )
{
- memcpy(&vio->mmio_large_read[addr - pa], p_data, size);
+ memcpy(&vio->mmio_large_read[bytes], p_data, size);
vio->mmio_large_read_bytes += size;
}
}
@@ -1151,9 +1163,13 @@ int hvm_emulate_one(
? sizeof(hvmemul_ctxt->insn_buf) : 0;
hvmemul_ctxt->exn_pending = 0;
+ vio->mmio_retrying = vio->mmio_retry;
+ vio->mmio_retry = 0;
rc = x86_emulate(&hvmemul_ctxt->ctxt, &hvm_emulate_ops);
+ if ( rc == X86EMUL_OKAY && vio->mmio_retry )
+ rc = X86EMUL_RETRY;
if ( rc != X86EMUL_RETRY )
vio->mmio_large_read_bytes = vio->mmio_large_write_bytes = 0;
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 77698c4..6e344e4 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -294,12 +294,21 @@ void hvm_io_assist(void)
static int dpci_ioport_read(uint32_t mport, ioreq_t *p)
{
- int i, step = p->df ? -p->size : p->size;
+ struct hvm_vcpu_io *vio = ¤t->arch.hvm_vcpu.hvm_io;
+ int rc = X86EMUL_OKAY, i, step = p->df ? -p->size : p->size;
uint32_t data = 0;
for ( i = 0; i < p->count; i++ )
{
- switch ( p->size )
+ 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 switch ( p->size )
{
case 1:
data = inb(mport);
@@ -316,22 +325,51 @@ static int dpci_ioport_read(uint32_t mport, ioreq_t *p)
if ( p->data_is_ptr )
{
- int ret;
- ret = hvm_copy_to_guest_phys(p->data + step * i, &data, p->size);
- if ( (ret == HVMCOPY_gfn_paged_out) ||
- (ret == HVMCOPY_gfn_shared) )
- return X86EMUL_RETRY;
+ switch ( hvm_copy_to_guest_phys(p->data + step * i,
+ &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:
+ ASSERT(0);
+ /* fall through */
+ default:
+ rc = X86EMUL_UNHANDLEABLE;
+ break;
+ }
+ if ( rc != X86EMUL_OKAY)
+ break;
}
else
p->data = data;
}
-
- return X86EMUL_OKAY;
+
+ if ( rc == X86EMUL_RETRY )
+ {
+ vio->mmio_retry = 1;
+ vio->mmio_large_read_bytes = p->size;
+ memcpy(vio->mmio_large_read, &data, p->size);
+ }
+
+ if ( i != 0 )
+ {
+ p->count = i;
+ rc = X86EMUL_OKAY;
+ }
+
+ return rc;
}
static int dpci_ioport_write(uint32_t mport, ioreq_t *p)
{
- int i, step = p->df ? -p->size : p->size;
+ int rc = X86EMUL_OKAY, i, step = p->df ? -p->size : p->size;
uint32_t data;
for ( i = 0; i < p->count; i++ )
@@ -346,7 +384,8 @@ static int dpci_ioport_write(uint32_t mport, ioreq_t *p)
break;
case HVMCOPY_gfn_paged_out:
case HVMCOPY_gfn_shared:
- return X86EMUL_RETRY;
+ rc = X86EMUL_RETRY;
+ break;
case HVMCOPY_bad_gfn_to_mfn:
data = ~0;
break;
@@ -354,8 +393,11 @@ static int dpci_ioport_write(uint32_t mport, ioreq_t *p)
ASSERT(0);
/* fall through */
default:
- return X86EMUL_UNHANDLEABLE;
+ rc = X86EMUL_UNHANDLEABLE;
+ break;
}
+ if ( rc != X86EMUL_OKAY)
+ break;
}
switch ( p->size )
@@ -374,7 +416,16 @@ static int dpci_ioport_write(uint32_t mport, ioreq_t *p)
}
}
- return X86EMUL_OKAY;
+ if ( rc == X86EMUL_RETRY )
+ current->arch.hvm_vcpu.hvm_io.mmio_retry = 1;
+
+ if ( i != 0 )
+ {
+ p->count = i;
+ rc = X86EMUL_OKAY;
+ }
+
+ return rc;
}
int dpci_ioport_intercept(ioreq_t *p)
diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h
index e8b8cd7..1abb364 100644
--- a/xen/include/asm-x86/hvm/vcpu.h
+++ b/xen/include/asm-x86/hvm/vcpu.h
@@ -66,6 +66,11 @@ struct hvm_vcpu_io {
/* We may write up to m256 as a number of device-model transactions. */
unsigned int mmio_large_write_bytes;
paddr_t mmio_large_write_pa;
+ /*
+ * 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;
};
#define VMCX_EADDR (~0ULL)
--
generated by git-patchbot for /home/xen/git/xen.git#master
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