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vmd: Bypass MSI/MSI-X remapping when possible.

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By default all VMD devices remap children MSI/MSI-X interrupts into their
own.  It creates additional isolation, but also complicates things due to
sharing, etc.  Fortunately some VMD devices can bypass the remapping.
Add tunable to control it for remap testing or if something go wrong.

MFC after:	2 weeks
This commit is contained in:
Alexander Motin 2022-10-06 12:15:25 -04:00
parent 9cabef3d14
commit c28220d866
2 changed files with 63 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
share/man/man4/vmd.4
View File

@ -27,7 +27,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd August 31, 2021
.Dd October 6, 2022
.Dt VMD 4
.Os
.Sh NAME
@ -57,6 +57,11 @@ The following tunables are settable via
or
.Xr sysctl 8 :
.Bl -tag -width indent
.It Va hw.vmd.bypass_msi
By default all VMD devices remap children MSI/MSI-X interrupts into their
own. It creates additional isolation, but also complicates things due to
sharing, etc. Fortunately some VMD devices can bypass the remapping.
Defaults to 1.
.It Va hw.vmd.max_msi
Limits number of Message Signaled Interrupt (MSI) vectors allowed to each
child device.

59
sys/dev/vmd/vmd.c
View File

@ -65,12 +65,14 @@ struct vmd_type {
int flags;
#define BUS_RESTRICT 1
#define VECTOR_OFFSET 2
#define CAN_BYPASS_MSI 4
};
#define VMD_CAP 0x40
#define VMD_BUS_RESTRICT 0x1
#define VMD_CONFIG 0x44
#define VMD_BYPASS_MSI 0x2
#define VMD_BUS_START(x) ((x >> 8) & 0x3)
#define VMD_LOCK 0x70
@ -78,6 +80,15 @@ struct vmd_type {
SYSCTL_NODE(_hw, OID_AUTO, vmd, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
"Intel Volume Management Device tuning parameters");
/*
* By default all VMD devices remap children MSI/MSI-X interrupts into their
* own. It creates additional isolation, but also complicates things due to
* sharing, etc. Fortunately some VMD devices can bypass the remapping.
*/
static int vmd_bypass_msi = 1;
SYSCTL_INT(_hw_vmd, OID_AUTO, bypass_msi, CTLFLAG_RWTUN, &vmd_bypass_msi, 0,
"Bypass MSI remapping on capable hardware");
/*
* All MSIs within a group share address, so VMD can't distinguish them.
* It makes no sense to use more than one per device, only if required by
@ -97,7 +108,7 @@ SYSCTL_INT(_hw_vmd, OID_AUTO, max_msix, CTLFLAG_RWTUN, &vmd_max_msix, 0,
static struct vmd_type vmd_devs[] = {
{ 0x8086, 0x201d, "Intel Volume Management Device", 0 },
{ 0x8086, 0x28c0, "Intel Volume Management Device", BUS_RESTRICT },
{ 0x8086, 0x28c0, "Intel Volume Management Device", BUS_RESTRICT | CAN_BYPASS_MSI },
{ 0x8086, 0x467f, "Intel Volume Management Device", BUS_RESTRICT | VECTOR_OFFSET },
{ 0x8086, 0x4c3d, "Intel Volume Management Device", BUS_RESTRICT | VECTOR_OFFSET },
{ 0x8086, 0x9a0b, "Intel Volume Management Device", BUS_RESTRICT | VECTOR_OFFSET },
@ -216,6 +227,19 @@ vmd_write_config(device_t dev, u_int b, u_int s, u_int f, u_int reg,
}
}
static void
vmd_set_msi_bypass(device_t dev, bool enable)
{
uint16_t val;
val = pci_read_config(dev, VMD_CONFIG, 2);
if (enable)
val |= VMD_BYPASS_MSI;
else
val &= ~VMD_BYPASS_MSI;
pci_write_config(dev, VMD_CONFIG, val, 2);
}
static int
vmd_intr(void *arg)
{
@ -340,7 +364,10 @@ vmd_attach(device_t dev)
LIST_INIT(&sc->vmd_users);
sc->vmd_fist_vector = (t->flags & VECTOR_OFFSET) ? 1 : 0;
sc->vmd_msix_count = pci_msix_count(dev);
if (pci_alloc_msix(dev, &sc->vmd_msix_count) == 0) {
if (vmd_bypass_msi && (t->flags & CAN_BYPASS_MSI)) {
sc->vmd_msix_count = 0;
vmd_set_msi_bypass(dev, true);
} else if (pci_alloc_msix(dev, &sc->vmd_msix_count) == 0) {
sc->vmd_irq = malloc(sizeof(struct vmd_irq) *
sc->vmd_msix_count, M_DEVBUF, M_WAITOK | M_ZERO);
for (i = 0; i < sc->vmd_msix_count; i++) {
@ -362,6 +389,7 @@ vmd_attach(device_t dev)
goto fail;
}
}
vmd_set_msi_bypass(dev, false);
}
sc->vmd_dma_tag = bus_get_dma_tag(dev);
@ -386,6 +414,8 @@ vmd_detach(device_t dev)
error = device_delete_children(dev);
if (error)
return (error);
if (sc->vmd_msix_count == 0)
vmd_set_msi_bypass(dev, false);
vmd_free(sc);
return (0);
}
@ -482,6 +512,11 @@ vmd_alloc_msi(device_t dev, device_t child, int count, int maxcount,
struct vmd_irq_user *u;
int i, ibest = 0, best = INT_MAX;
if (sc->vmd_msix_count == 0) {
return (PCIB_ALLOC_MSI(device_get_parent(device_get_parent(dev)),
child, count, maxcount, irqs));
}
if (count > vmd_max_msi)
return (ENOSPC);
LIST_FOREACH(u, &sc->vmd_users, viu_link) {
@ -513,6 +548,11 @@ vmd_release_msi(device_t dev, device_t child, int count, int *irqs)
struct vmd_softc *sc = device_get_softc(dev);
struct vmd_irq_user *u;
if (sc->vmd_msix_count == 0) {
return (PCIB_RELEASE_MSI(device_get_parent(device_get_parent(dev)),
child, count, irqs));
}
LIST_FOREACH(u, &sc->vmd_users, viu_link) {
if (u->viu_child == child) {
sc->vmd_irq[u->viu_vector].vi_nusers -= count;
@ -531,6 +571,11 @@ vmd_alloc_msix(device_t dev, device_t child, int *irq)
struct vmd_irq_user *u;
int i, ibest = 0, best = INT_MAX;
if (sc->vmd_msix_count == 0) {
return (PCIB_ALLOC_MSIX(device_get_parent(device_get_parent(dev)),
child, irq));
}
i = 0;
LIST_FOREACH(u, &sc->vmd_users, viu_link) {
if (u->viu_child == child)
@ -562,6 +607,11 @@ vmd_release_msix(device_t dev, device_t child, int irq)
struct vmd_softc *sc = device_get_softc(dev);
struct vmd_irq_user *u;
if (sc->vmd_msix_count == 0) {
return (PCIB_RELEASE_MSIX(device_get_parent(device_get_parent(dev)),
child, irq));
}
LIST_FOREACH(u, &sc->vmd_users, viu_link) {
if (u->viu_child == child &&
sc->vmd_irq[u->viu_vector].vi_irq == irq) {
@ -580,6 +630,11 @@ vmd_map_msi(device_t dev, device_t child, int irq, uint64_t *addr, uint32_t *dat
struct vmd_softc *sc = device_get_softc(dev);
int i;
if (sc->vmd_msix_count == 0) {
return (PCIB_MAP_MSI(device_get_parent(device_get_parent(dev)),
child, irq, addr, data));
}
for (i = sc->vmd_fist_vector; i < sc->vmd_msix_count; i++) {
if (sc->vmd_irq[i].vi_irq == irq)
break;