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Re: [Qemu-devel] [PATCH v8 12/17] pci: Convert msi_init() to Error and f


From: Marcel Apfelbaum
Subject: Re: [Qemu-devel] [PATCH v8 12/17] pci: Convert msi_init() to Error and fix callers to check it
Date: Mon, 13 Jun 2016 14:53:38 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0

On 06/13/2016 02:07 PM, Markus Armbruster wrote:
Marcel Apfelbaum <address@hidden> writes:

On 06/10/2016 12:54 PM, Cao jin wrote:
msi_init() reports errors with error_report(), which is wrong
when it's used in realize().

Fix by converting it to Error.

Fix its callers to handle failure instead of ignoring it.

For those callers who don't handle the failure, it might happen:
when user want msi on, but he doesn't get what he want because of
msi_init fails silently.

cc: Gerd Hoffmann <address@hidden>
cc: John Snow <address@hidden>
cc: Dmitry Fleytman <address@hidden>
cc: Jason Wang <address@hidden>
cc: Michael S. Tsirkin <address@hidden>
cc: Hannes Reinecke <address@hidden>
cc: Paolo Bonzini <address@hidden>
cc: Alex Williamson <address@hidden>
cc: Markus Armbruster <address@hidden>
cc: Marcel Apfelbaum <address@hidden>

Reviewed-by: Markus Armbruster <address@hidden>
Signed-off-by: Cao jin <address@hidden>
---
   hw/audio/intel-hda.c               | 24 ++++++++++++++++++++----
   hw/ide/ich.c                       | 15 +++++++++------
   hw/net/e1000e.c                    |  8 ++------
   hw/net/vmxnet3.c                   | 37 ++++++++++++-------------------------
   hw/pci-bridge/ioh3420.c            |  6 +++++-
   hw/pci-bridge/pci_bridge_dev.c     | 20 ++++++++++++++++----
   hw/pci-bridge/xio3130_downstream.c |  6 +++++-
   hw/pci-bridge/xio3130_upstream.c   |  6 +++++-
   hw/pci/msi.c                       | 11 ++++++++---
   hw/scsi/megasas.c                  | 26 +++++++++++++++++++++-----
   hw/scsi/mptsas.c                   | 31 ++++++++++++++++++++++++-------
   hw/scsi/vmw_pvscsi.c               |  2 +-
   hw/usb/hcd-xhci.c                  | 23 +++++++++++++++++++----
   hw/vfio/pci.c                      |  7 +++++--
   include/hw/pci/msi.h               |  3 ++-
   15 files changed, 154 insertions(+), 71 deletions(-)

diff --git a/hw/audio/intel-hda.c b/hw/audio/intel-hda.c
index 6b4dda0..82101f8 100644
--- a/hw/audio/intel-hda.c
+++ b/hw/audio/intel-hda.c
@@ -1135,6 +1135,8 @@ static void intel_hda_realize(PCIDevice *pci, Error 
**errp)
   {
       IntelHDAState *d = INTEL_HDA(pci);
       uint8_t *conf = d->pci.config;
+    Error *err = NULL;
+    int ret;

       d->name = object_get_typename(OBJECT(d));

@@ -1143,13 +1145,27 @@ static void intel_hda_realize(PCIDevice *pci, Error 
**errp)
       /* HDCTL off 0x40 bit 0 selects signaling mode (1-HDA, 0 - Ac97) 18.1.19 
*/
       conf[0x40] = 0x01;

+    if (d->msi != ON_OFF_AUTO_OFF) {
+        ret = msi_init(&d->pci, d->old_msi_addr ? 0x50 : 0x60,
+                       1, true, false, &err);
+        /* Any error other than -ENOTSUP(board's MSI support is broken)
+         * is a programming error */
+        assert(!ret || ret == -ENOTSUP);
+        if (ret && d->msi == ON_OFF_AUTO_ON) {
+            /* Can't satisfy user's explicit msi=on request, fail */
+            error_append_hint(&err, "You have to use msi=auto (default) or "
+                    "msi=off with this machine type.\n");
+            error_propagate(errp, err);
+            return;
+        }
+        assert(!err || d->msi == ON_OFF_AUTO_AUTO);
+        /* With msi=auto, we fall back to MSI off silently */
+        error_free(err);
+    }
+
       memory_region_init_io(&d->mmio, OBJECT(d), &intel_hda_mmio_ops, d,
                             "intel-hda", 0x4000);
       pci_register_bar(&d->pci, 0, 0, &d->mmio);
-    if (d->msi != ON_OFF_AUTO_OFF) {
-         /* TODO check for errors */
-        msi_init(&d->pci, d->old_msi_addr ? 0x50 : 0x60, 1, true, false);
-    }

       hda_codec_bus_init(DEVICE(pci), &d->codecs, sizeof(d->codecs),
                          intel_hda_response, intel_hda_xfer);
diff --git a/hw/ide/ich.c b/hw/ide/ich.c
index 0a13334..084bef8 100644
--- a/hw/ide/ich.c
+++ b/hw/ide/ich.c
@@ -68,7 +68,6 @@
   #include <hw/isa/isa.h>
   #include "sysemu/block-backend.h"
   #include "sysemu/dma.h"
-
   #include <hw/ide/pci.h>
   #include <hw/ide/ahci.h>

@@ -111,6 +110,15 @@ static void pci_ich9_ahci_realize(PCIDevice *dev, Error 
**errp)
       int sata_cap_offset;
       uint8_t *sata_cap;
       d = ICH_AHCI(dev);
+    int ret;
+
+    /* Although the AHCI 1.3 specification states that the first capability
+     * should be PMCAP, the Intel ICH9 data sheet specifies that the ICH9
+     * AHCI device puts the MSI capability first, pointing to 0x80. */
+    ret = msi_init(dev, ICH9_MSI_CAP_OFFSET, 1, true, false, NULL);
+    /* Any error other than -ENOTSUP(board's MSI support is broken)
+     * is a programming error.  Fall back to INTx silently on -ENOTSUP */
+    assert(!ret || ret == -ENOTSUP);

       ahci_realize(&d->ahci, DEVICE(dev), pci_get_address_space(dev), 6);

@@ -142,11 +150,6 @@ static void pci_ich9_ahci_realize(PCIDevice *dev, Error 
**errp)
       pci_set_long(sata_cap + SATA_CAP_BAR,
                    (ICH9_IDP_BAR + 0x4) | (ICH9_IDP_INDEX_LOG2 << 4));
       d->ahci.idp_offset = ICH9_IDP_INDEX;
-
-    /* Although the AHCI 1.3 specification states that the first capability
-     * should be PMCAP, the Intel ICH9 data sheet specifies that the ICH9
-     * AHCI device puts the MSI capability first, pointing to 0x80. */
-    msi_init(dev, ICH9_MSI_CAP_OFFSET, 1, true, false);
   }

   static void pci_ich9_uninit(PCIDevice *dev)
diff --git a/hw/net/e1000e.c b/hw/net/e1000e.c
index 692283f..a06d184 100644
--- a/hw/net/e1000e.c
+++ b/hw/net/e1000e.c
@@ -268,13 +268,9 @@ e1000e_init_msi(E1000EState *s)
   {
       int res;

-    res = msi_init(PCI_DEVICE(s),
-                   0xD0,   /* MSI capability offset              */
-                   1,      /* MAC MSI interrupts                 */
-                   true,   /* 64-bit message addresses supported */
-                   false); /* Per vector mask supported          */
+    res = msi_init(PCI_DEVICE(s), 0xD0, 1, true, false, NULL);


Why did you chose to remove author's comments?


-    if (res > 0) {
+    if (!res) {
           s->intr_state |= E1000E_USE_MSI;
       } else {
           trace_e1000e_msi_init_fail(res);
diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index d978976..63f8904 100644
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -2197,27 +2197,6 @@ vmxnet3_cleanup_msix(VMXNET3State *s)
       }
   }

-#define VMXNET3_USE_64BIT         (true)
-#define VMXNET3_PER_VECTOR_MASK   (false)
-
-static bool
-vmxnet3_init_msi(VMXNET3State *s)
-{
-    PCIDevice *d = PCI_DEVICE(s);
-    int res;
-
-    res = msi_init(d, VMXNET3_MSI_OFFSET(s), VMXNET3_MAX_NMSIX_INTRS,
-                   VMXNET3_USE_64BIT, VMXNET3_PER_VECTOR_MASK);
-    if (0 > res) {
-        VMW_WRPRN("Failed to initialize MSI, error %d", res);
-        s->msi_used = false;
-    } else {
-        s->msi_used = true;
-    }
-
-    return s->msi_used;
-}
-
   static void
   vmxnet3_cleanup_msi(VMXNET3State *s)
   {
@@ -2279,10 +2258,15 @@ static uint64_t vmxnet3_device_serial_num(VMXNET3State 
*s)
       return dsn_payload;
   }

+
+#define VMXNET3_USE_64BIT         (true)
+#define VMXNET3_PER_VECTOR_MASK   (false)
+
   static void vmxnet3_pci_realize(PCIDevice *pci_dev, Error **errp)
   {
       DeviceState *dev = DEVICE(pci_dev);
       VMXNET3State *s = VMXNET3(pci_dev);
+    int ret;

       VMW_CBPRN("Starting init...");

@@ -2306,14 +2290,17 @@ static void vmxnet3_pci_realize(PCIDevice *pci_dev, 
Error **errp)
       /* Interrupt pin A */
       pci_dev->config[PCI_INTERRUPT_PIN] = 0x01;

+    ret = msi_init(pci_dev, VMXNET3_MSI_OFFSET(s), VMXNET3_MAX_NMSIX_INTRS,
+                   VMXNET3_USE_64BIT, VMXNET3_PER_VECTOR_MASK, NULL);
+    /* Any error other than -ENOTSUP(board's MSI support is broken)
+     * is a programming error. Fall back to INTx silently on -ENOTSUP */
+    assert(!ret || ret == -ENOTSUP);
+    s->msi_used = !ret;
+
       if (!vmxnet3_init_msix(s)) {
           VMW_WRPRN("Failed to initialize MSI-X, configuration is 
inconsistent.");
       }

-    if (!vmxnet3_init_msi(s)) {
-        VMW_WRPRN("Failed to initialize MSI, configuration is inconsistent.");
-    }
-
       vmxnet3_net_init(s);

       if (pci_is_express(pci_dev)) {
diff --git a/hw/pci-bridge/ioh3420.c b/hw/pci-bridge/ioh3420.c
index b4a7806..93c6f0b 100644
--- a/hw/pci-bridge/ioh3420.c
+++ b/hw/pci-bridge/ioh3420.c
@@ -25,6 +25,7 @@
   #include "hw/pci/msi.h"
   #include "hw/pci/pcie.h"
   #include "ioh3420.h"
+#include "qapi/error.h"

   #define PCI_DEVICE_ID_IOH_EPORT         0x3420  /* D0:F0 express mode */
   #define PCI_DEVICE_ID_IOH_REV           0x2
@@ -97,6 +98,7 @@ static int ioh3420_initfn(PCIDevice *d)
       PCIEPort *p = PCIE_PORT(d);
       PCIESlot *s = PCIE_SLOT(d);
       int rc;
+    Error *err = NULL;

       pci_bridge_initfn(d, TYPE_PCIE_BUS);
       pcie_port_init_reg(d);
@@ -109,8 +111,10 @@ static int ioh3420_initfn(PCIDevice *d)

       rc = msi_init(d, IOH_EP_MSI_OFFSET, IOH_EP_MSI_NR_VECTOR,
                     IOH_EP_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_64BIT,
-                  IOH_EP_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT);
+                  IOH_EP_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT, &err);
       if (rc < 0) {
+        assert(rc == -ENOTSUP);
+        error_report_err(err);
           goto err_bridge;
       }

diff --git a/hw/pci-bridge/pci_bridge_dev.c b/hw/pci-bridge/pci_bridge_dev.c
index 0fbecc4..c4d2c0b 100644
--- a/hw/pci-bridge/pci_bridge_dev.c
+++ b/hw/pci-bridge/pci_bridge_dev.c
@@ -54,6 +54,7 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
       PCIBridge *br = PCI_BRIDGE(dev);
       PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
       int err;
+    Error *local_err = NULL;

       pci_bridge_initfn(dev, TYPE_PCI_BUS);

@@ -75,12 +76,23 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
           goto slotid_error;
       }

-    if (bridge_dev->msi != ON_OFF_AUTO_OFF &&
-        msi_nonbroken) {
-        err = msi_init(dev, 0, 1, true, true);
-        if (err < 0) {
+    if (bridge_dev->msi != ON_OFF_AUTO_OFF) {
+        /* it means SHPC exists, because SHPC is required for MSI */

Is the other way around, MSI is needed by SHPC (but not compulsory)

+
+        err = msi_init(dev, 0, 1, true, true, &local_err);
+        /* Any error other than -ENOTSUP(board's MSI support is broken)
+         * is a programming error */
+        assert(!err || err == -ENOTSUP);
+        if (err && bridge_dev->msi == ON_OFF_AUTO_ON) {
+            /* Can't satisfy user's explicit msi=on request, fail */
+            error_append_hint(&local_err, "You have to use msi=auto (default) "
+                    "or msi=off with this machine type.\n");
+            error_report_err(local_err);
               goto msi_error;
           }
+        assert(!local_err || bridge_dev->msi == ON_OFF_AUTO_AUTO);
+        /* With msi=auto, we fall back to MSI off silently */
+        error_free(local_err);
       }

       if (shpc_present(dev)) {
diff --git a/hw/pci-bridge/xio3130_downstream.c 
b/hw/pci-bridge/xio3130_downstream.c
index e6d653d..f6149a3 100644
--- a/hw/pci-bridge/xio3130_downstream.c
+++ b/hw/pci-bridge/xio3130_downstream.c
@@ -24,6 +24,7 @@
   #include "hw/pci/msi.h"
   #include "hw/pci/pcie.h"
   #include "xio3130_downstream.h"
+#include "qapi/error.h"

   #define PCI_DEVICE_ID_TI_XIO3130D       0x8233  /* downstream port */
   #define XIO3130_REVISION                0x1
@@ -60,14 +61,17 @@ static int xio3130_downstream_initfn(PCIDevice *d)
       PCIEPort *p = PCIE_PORT(d);
       PCIESlot *s = PCIE_SLOT(d);
       int rc;
+    Error *err = NULL;

       pci_bridge_initfn(d, TYPE_PCIE_BUS);
       pcie_port_init_reg(d);

       rc = msi_init(d, XIO3130_MSI_OFFSET, XIO3130_MSI_NR_VECTOR,
                     XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_64BIT,
-                  XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT);
+                  XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT, &err);
       if (rc < 0) {
+        assert(rc == -ENOTSUP);
+        error_report_err(err);
           goto err_bridge;
       }

diff --git a/hw/pci-bridge/xio3130_upstream.c b/hw/pci-bridge/xio3130_upstream.c
index d976844..487edac 100644
--- a/hw/pci-bridge/xio3130_upstream.c
+++ b/hw/pci-bridge/xio3130_upstream.c
@@ -24,6 +24,7 @@
   #include "hw/pci/msi.h"
   #include "hw/pci/pcie.h"
   #include "xio3130_upstream.h"
+#include "qapi/error.h"

   #define PCI_DEVICE_ID_TI_XIO3130U       0x8232  /* upstream port */
   #define XIO3130_REVISION                0x2
@@ -56,14 +57,17 @@ static int xio3130_upstream_initfn(PCIDevice *d)
   {
       PCIEPort *p = PCIE_PORT(d);
       int rc;
+    Error *err = NULL;

       pci_bridge_initfn(d, TYPE_PCIE_BUS);
       pcie_port_init_reg(d);

       rc = msi_init(d, XIO3130_MSI_OFFSET, XIO3130_MSI_NR_VECTOR,
                     XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_64BIT,
-                  XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT);
+                  XIO3130_MSI_SUPPORTED_FLAGS & PCI_MSI_FLAGS_MASKBIT, &err);
       if (rc < 0) {
+        assert(rc == -ENOTSUP);
+        error_report_err(err);

Hi Jin, Markus

It looks a little weird to me to check for negative error code
and then assert for a specific error as the only "valid error".
Maybe we should assert inside msi_init to leave the callers "clean"?

I am well aware a lot of time was spent for this series, but I just
spotted it and I want to be sure we are doing it right.

Only the callers know how to handle these errors.  Let me explain using
the function comment:

  * -ENOTSUP means lacking msi support for a msi-capable platform.

Our board emulation is broken.  The device decides whether this is an
error (say because the user requested msi=on), or not.  If it isn't,
devices generally fall back to a non-MSI variant.

  * -EINVAL means capability overlap, happens when @offset is non-zero,
  *  also means a programming error, except device assignment, which can check
  *  if a real HW is broken.

For virtual devices, this is a programming error.  Such callers should
therefore abort.  But for device assignment, it's a physical device with
messed up capabilities --- not a programming error, aborting would be
inappropriate.  See vfio_msi_setup() for an example.


I missed the vfio scenario.
Now I got it.

Thanks!
Marcel






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