[src/trunk]: src/sys/dev add a quirk to disable MSI, and enable it for Intel ...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3fbed0242ba8
branches:  trunk
changeset: 936507:3fbed0242ba8
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Tue Jul 28 09:36:05 2020 +0000

description:
add a quirk to disable MSI, and enable it for Intel SSD DC P4500

this device seems to cause serious system responsiveness issues when configured
to use MSI, while it works fine when configured for either INTx or MSI-X

this is important so this works well under Xen Dom0, which doesn't
support MSI-X yet

fixes another issue reported as feedback for PR port-xen/55285 by Frank Kardel

diffstat:

 sys/dev/ic/nvmevar.h   |   3 ++-
 sys/dev/pci/nvme_pci.c |  16 ++++++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diffs (75 lines):

diff -r 2152c1594ff0 -r 3fbed0242ba8 sys/dev/ic/nvmevar.h
--- a/sys/dev/ic/nvmevar.h      Tue Jul 28 01:40:43 2020 +0000
+++ b/sys/dev/ic/nvmevar.h      Tue Jul 28 09:36:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmevar.h,v 1.20 2019/06/28 15:08:47 jmcneill Exp $    */
+/*     $NetBSD: nvmevar.h,v 1.21 2020/07/28 09:36:05 jdolecek Exp $    */
 /*     $OpenBSD: nvmevar.h,v 1.8 2016/04/14 11:18:32 dlg Exp $ */
 
 /*
@@ -140,6 +140,7 @@
 
        uint32_t                sc_quirks;
 #define        NVME_QUIRK_DELAY_B4_CHK_RDY     __BIT(0)
+#define        NVME_QUIRK_NOMSI                __BIT(1)
 
        char                    sc_modelname[81];
 };
diff -r 2152c1594ff0 -r 3fbed0242ba8 sys/dev/pci/nvme_pci.c
--- a/sys/dev/pci/nvme_pci.c    Tue Jul 28 01:40:43 2020 +0000
+++ b/sys/dev/pci/nvme_pci.c    Tue Jul 28 09:36:05 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvme_pci.c,v 1.27 2019/12/02 03:06:51 msaitoh Exp $    */
+/*     $NetBSD: nvme_pci.c,v 1.28 2020/07/28 09:36:05 jdolecek Exp $   */
 /*     $OpenBSD: nvme_pci.c,v 1.3 2016/04/14 11:18:32 dlg Exp $ */
 
 /*
@@ -43,7 +43,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvme_pci.c,v 1.27 2019/12/02 03:06:51 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvme_pci.c,v 1.28 2020/07/28 09:36:05 jdolecek Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -108,6 +108,8 @@
            NVME_QUIRK_DELAY_B4_CHK_RDY },
        { PCI_VENDOR_SAMSUNGELEC3, PCI_PRODUCT_SAMSUNGELEC3_172XAB,
            NVME_QUIRK_DELAY_B4_CHK_RDY },
+       { PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_DC_P4500_SSD,
+           NVME_QUIRK_NOMSI },
 };
 
 static const struct nvme_pci_quirk *
@@ -158,6 +160,10 @@
        else
                sc->sc_dmat = pa->pa_dmat;
 
+       quirk = nvme_pci_lookup_quirk(pa);
+       if (quirk != NULL)
+               sc->sc_quirks = quirk->quirks;
+
        pci_aprint_devinfo(pa, NULL);
 
        /* Map registers */
@@ -221,10 +227,6 @@
        sc->sc_softih = kmem_zalloc(
            sizeof(*sc->sc_softih) * psc->psc_nintrs, KM_SLEEP);
 
-       quirk = nvme_pci_lookup_quirk(pa);
-       if (quirk != NULL)
-               sc->sc_quirks = quirk->quirks;
-
        if (nvme_attach(sc) != 0) {
                /* error printed by nvme_attach() */
                goto softintr_free;
@@ -412,6 +414,8 @@
        }
 
        /* MSI */
+       if (sc->sc_quirks & NVME_QUIRK_NOMSI)
+               goto force_intx;
        counts[PCI_INTR_TYPE_MSI] = pci_msi_count(pa->pa_pc, pa->pa_tag);
        if (counts[PCI_INTR_TYPE_MSI] > 0) {
                while (counts[PCI_INTR_TYPE_MSI] > ncpu + 1) {