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[Qemu-devel] [PULL 17/54] scsi: esp: Defer command completion until prev
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 17/54] scsi: esp: Defer command completion until previous interrupts have been handled |
Date: |
Wed, 12 Dec 2018 16:22:38 +0100 |
From: Guenter Roeck <address@hidden>
The guest OS reads RSTAT, RSEQ, and RINTR, and expects those registers
to reflect a consistent state. However, it is possible that the registers
can change after RSTAT was read, but before RINTR is read, when
esp_command_complete() is called.
Guest OS qemu
-------- ----
[handle interrupt]
Read RSTAT
esp_command_complete()
RSTAT = STAT_ST
esp_dma_done()
RSTAT |= STAT_TC
RSEQ = 0
RINTR = INTR_BS
Read RSEQ
Read RINTR RINTR = 0
RSTAT &= ~STAT_TC
RSEQ = SEQ_CD
The guest OS would then try to handle INTR_BS combined with an old
value of RSTAT. This sometimes resulted in lost events, spurious
interrupts, guest OS confusion, and stalled SCSI operations.
A typical guest error log (observed with various versions of Linux)
looks as follows.
scsi host1: Spurious irq, sreg=13.
...
scsi host1: Aborting command [84531f10:2a]
scsi host1: Current command [f882eea8:35]
scsi host1: Queued command [84531f10:2a]
scsi host1: Active command [f882eea8:35]
scsi host1: Dumping command log
scsi host1: ent[15] CMD val[44] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[00]
event[0c]
scsi host1: ent[16] CMD val[01] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02]
event[0c]
scsi host1: ent[17] CMD val[43] sreg[90] seqreg[00] sreg2[00] ireg[20] ss[02]
event[0c]
scsi host1: ent[18] EVENT val[0d] sreg[92] seqreg[04] sreg2[00] ireg[18] ss[00]
event[0c]
...
Defer handling command completion until previous interrupts have been
handled to fix the problem.
Signed-off-by: Guenter Roeck <address@hidden>
---
hw/scsi/esp-pci.c | 4 ++--
hw/scsi/esp.c | 33 ++++++++++++++++++++++++++-------
hw/scsi/trace-events | 1 +
include/hw/scsi/esp.h | 2 ++
4 files changed, 31 insertions(+), 9 deletions(-)
diff --git a/hw/scsi/esp-pci.c b/hw/scsi/esp-pci.c
index d956909..6b0bbb9 100644
--- a/hw/scsi/esp-pci.c
+++ b/hw/scsi/esp-pci.c
@@ -313,8 +313,8 @@ static void esp_pci_hard_reset(DeviceState *dev)
static const VMStateDescription vmstate_esp_pci_scsi = {
.name = "pciespscsi",
- .version_id = 0,
- .minimum_version_id = 0,
+ .version_id = 1,
+ .minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_PCI_DEVICE(parent_obj, PCIESPState),
VMSTATE_BUFFER_UNSAFE(dma_regs, PCIESPState, 0, 8 * sizeof(uint32_t)),
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 630d923..ca8b36c 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -286,11 +286,8 @@ static void esp_do_dma(ESPState *s)
esp_dma_done(s);
}
-void esp_command_complete(SCSIRequest *req, uint32_t status,
- size_t resid)
+static void esp_report_command_complete(ESPState *s, uint32_t status)
{
- ESPState *s = req->hba_private;
-
trace_esp_command_complete();
if (s->ti_size != 0) {
trace_esp_command_complete_unexpected();
@@ -311,6 +308,23 @@ void esp_command_complete(SCSIRequest *req, uint32_t
status,
}
}
+void esp_command_complete(SCSIRequest *req, uint32_t status,
+ size_t resid)
+{
+ ESPState *s = req->hba_private;
+
+ if (s->rregs[ESP_RSTAT] & STAT_INT) {
+ /* Defer handling command complete until the previous
+ * interrupt has been handled.
+ */
+ trace_esp_command_complete_deferred();
+ s->deferred_status = status;
+ s->deferred_complete = true;
+ return;
+ }
+ esp_report_command_complete(s, status);
+}
+
void esp_transfer_data(SCSIRequest *req, uint32_t len)
{
ESPState *s = req->hba_private;
@@ -422,7 +436,10 @@ uint64_t esp_reg_read(ESPState *s, uint32_t saddr)
s->rregs[ESP_RSTAT] &= ~STAT_TC;
s->rregs[ESP_RSEQ] = SEQ_CD;
esp_lower_irq(s);
-
+ if (s->deferred_complete) {
+ esp_report_command_complete(s, s->deferred_status);
+ s->deferred_complete = false;
+ }
return old_val;
case ESP_TCHI:
/* Return the unique id if the value has never been written */
@@ -582,6 +599,8 @@ const VMStateDescription vmstate_esp = {
VMSTATE_UINT32(ti_wptr, ESPState),
VMSTATE_BUFFER(ti_buf, ESPState),
VMSTATE_UINT32(status, ESPState),
+ VMSTATE_UINT32(deferred_status, ESPState),
+ VMSTATE_BOOL(deferred_complete, ESPState),
VMSTATE_UINT32(dma, ESPState),
VMSTATE_PARTIAL_BUFFER(cmdbuf, ESPState, 16),
VMSTATE_BUFFER_START_MIDDLE_V(cmdbuf, ESPState, 16, 4),
@@ -671,8 +690,8 @@ static void sysbus_esp_hard_reset(DeviceState *dev)
static const VMStateDescription vmstate_sysbus_esp_scsi = {
.name = "sysbusespscsi",
- .version_id = 0,
- .minimum_version_id = 0,
+ .version_id = 1,
+ .minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_STRUCT(esp, SysBusESPState, 0, vmstate_esp, ESPState),
VMSTATE_END_OF_LIST()
diff --git a/hw/scsi/trace-events b/hw/scsi/trace-events
index 0fb6a99..2fe8a7c 100644
--- a/hw/scsi/trace-events
+++ b/hw/scsi/trace-events
@@ -167,6 +167,7 @@ esp_handle_satn_stop(uint32_t cmdlen) "cmdlen %d"
esp_write_response(uint32_t status) "Transfer status (status=%d)"
esp_do_dma(uint32_t cmdlen, uint32_t len) "command len %d + %d"
esp_command_complete(void) "SCSI Command complete"
+esp_command_complete_deferred(void) "SCSI Command complete deferred"
esp_command_complete_unexpected(void) "SCSI command completed unexpectedly"
esp_command_complete_fail(void) "Command failed"
esp_transfer_data(uint32_t dma_left, int32_t ti_size) "transfer %d/%d"
diff --git a/include/hw/scsi/esp.h b/include/hw/scsi/esp.h
index 682a0d2..adab63d 100644
--- a/include/hw/scsi/esp.h
+++ b/include/hw/scsi/esp.h
@@ -23,6 +23,8 @@ struct ESPState {
int32_t ti_size;
uint32_t ti_rptr, ti_wptr;
uint32_t status;
+ uint32_t deferred_status;
+ bool deferred_complete;
uint32_t dma;
uint8_t ti_buf[TI_BUFSZ];
SCSIBus bus;
--
1.8.3.1
- [Qemu-devel] [PULL 03/54] checkpatch: fix premature exit when no input or --mailback, (continued)
- [Qemu-devel] [PULL 03/54] checkpatch: fix premature exit when no input or --mailback, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 06/54] checkpatch: colorize output to terminal, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 25/54] qemu/queue.h: do not access tqe_prev directly, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 24/54] compiler.h: Add an explicit check for the compiler version, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 13/54] block/iscsi: take iscsilun->mutex in iscsi_timed_check_events(), Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 16/54] esp-pci: Fix status register write erase control, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 15/54] block/iscsi: cancel libiscsi task when ABORT TASK TMF completes, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 02/54] vhost-user-bridge: fix "unknown type name" compilation error, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 26/54] vfio: make vfio_address_spaces static, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 22/54] test: execute g_test_run when tests are skipped, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 17/54] scsi: esp: Defer command completion until previous interrupts have been handled,
Paolo Bonzini <=
- [Qemu-devel] [PULL 21/54] RFC: qga: drop < Vista compatibility, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 19/54] build-sys: move windows defines in osdep.h header, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 10/54] memory: update coalesced_range on transaction_commit, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 28/54] qemu/queue.h: typedef QTAILQ heads, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 12/54] block/iscsi: drop unused IscsiAIOCB->buf field, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 32/54] checkpatch: warn about qemu/queue.h head structs that are not typedef-ed, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 34/54] configure: Remove obsolete check for Clang < 3.2, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 23/54] test: replace gtester with a TAP driver, Paolo Bonzini, 2018/12/12
- [Qemu-devel] [PULL 31/54] qemu/queue.h: simplify reverse access to QTAILQ, Paolo Bonzini, 2018/12/12