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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v9 22/28] ARM: vITS: handle MOVI command
On Thu, 11 May 2017, Andre Przywara wrote:
> The MOVI command moves the interrupt affinity from one redistributor
> (read: VCPU) to another.
> For now migration of "live" LPIs is not yet implemented, but we store
> the changed affinity in the host LPI structure and in our virtual ITTE.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> xen/arch/arm/gic-v3-its.c | 30 ++++++++++++++++++++
> xen/arch/arm/gic-v3-lpi.c | 15 ++++++++++
> xen/arch/arm/vgic-v3-its.c | 59
> ++++++++++++++++++++++++++++++++++++++++
> xen/include/asm-arm/gic_v3_its.h | 4 +++
> 4 files changed, 108 insertions(+)
>
> diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
> index 8a50f7d..f00597e 100644
> --- a/xen/arch/arm/gic-v3-its.c
> +++ b/xen/arch/arm/gic-v3-its.c
> @@ -915,6 +915,36 @@ struct pending_irq *gicv3_assign_guest_event(struct
> domain *d,
> return pirq;
> }
>
> +/* Changes the target VCPU for a given host LPI assigned to a domain. */
> +int gicv3_lpi_change_vcpu(struct domain *d, paddr_t vdoorbell,
> + uint32_t vdevid, uint32_t veventid,
> + unsigned int vcpu_id)
> +{
> + uint32_t host_lpi;
> + struct its_device *dev;
> +
> + spin_lock(&d->arch.vgic.its_devices_lock);
> + dev = get_its_device(d, vdoorbell, vdevid);
> + if ( dev )
> + host_lpi = get_host_lpi(dev, veventid);
> + else
> + host_lpi = 0;
> + spin_unlock(&d->arch.vgic.its_devices_lock);
> +
> + if ( !host_lpi )
> + return -ENOENT;
> +
> + /*
> + * TODO: This just changes the virtual affinity, the physical LPI
> + * still stays on the same physical CPU.
> + * Consider to move the physical affinity to the pCPU running the new
> + * vCPU. However this requires scheduling a host ITS command.
> + */
> + gicv3_lpi_update_host_vcpuid(host_lpi, vcpu_id);
> +
> + return 0;
> +}
> +
> /* Scan the DT for any ITS nodes and create a list of host ITSes out of it.
> */
> void gicv3_its_dt_init(const struct dt_device_node *node)
> {
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index d427539..6af5ad9 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -225,6 +225,21 @@ void gicv3_lpi_update_host_entry(uint32_t host_lpi, int
> domain_id,
> write_u64_atomic(&hlpip->data, hlpi.data);
> }
>
> +int gicv3_lpi_update_host_vcpuid(uint32_t host_lpi, unsigned int vcpu_id)
> +{
> + union host_lpi *hlpip;
> +
> + ASSERT(host_lpi >= LPI_OFFSET);
> +
> + host_lpi -= LPI_OFFSET;
> +
> + hlpip = &lpi_data.host_lpis[host_lpi / HOST_LPIS_PER_PAGE][host_lpi %
> HOST_LPIS_PER_PAGE];
> +
> + write_u16_atomic(&hlpip->vcpu_id, vcpu_id);
> +
> + return 0;
> +}
> +
> static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
> {
> uint64_t val;
> diff --git a/xen/arch/arm/vgic-v3-its.c b/xen/arch/arm/vgic-v3-its.c
> index c5c0e5e..ef7c78f 100644
> --- a/xen/arch/arm/vgic-v3-its.c
> +++ b/xen/arch/arm/vgic-v3-its.c
> @@ -670,6 +670,59 @@ out_remove_mapping:
> return ret;
> }
>
> +static int its_handle_movi(struct virt_its *its, uint64_t *cmdptr)
> +{
> + uint32_t devid = its_cmd_get_deviceid(cmdptr);
> + uint32_t eventid = its_cmd_get_id(cmdptr);
> + uint16_t collid = its_cmd_get_collection(cmdptr);
> + unsigned long flags;
> + struct pending_irq *p;
> + struct vcpu *ovcpu, *nvcpu;
> + uint32_t vlpi;
> + int ret = -1;
> +
> + spin_lock(&its->its_lock);
> + /* Check for a mapped LPI and get the LPI number. */
> + if ( !read_itte_locked(its, devid, eventid, &ovcpu, &vlpi) )
> + goto out_unlock;
> +
> + if ( vlpi == INVALID_LPI )
> + goto out_unlock;
> +
> + /* Check the new collection ID and get the new VCPU pointer */
> + nvcpu = get_vcpu_from_collection(its, collid);
> + if ( !nvcpu )
> + goto out_unlock;
> +
> + p = gicv3_its_get_event_pending_irq(its->d, its->doorbell_address,
> + devid, eventid);
> + if ( unlikely(!p) )
> + goto out_unlock;
> +
> + spin_lock_irqsave(&ovcpu->arch.vgic.lock, flags);
> +
> + /* Update our cached vcpu_id in the pending_irq. */
> + p->lpi_vcpu_id = nvcpu->vcpu_id;
I think we need to call gicv3_lpi_update_host_vcpuid here.
gicv3_lpi_update_host_vcpuid and this line change the vcpu target: they
need to be called in a region that is protected by both its_lock and
v->arch.vgic.lock.
In addition, right before calling gicv3_lpi_update_host_vcpuid, we need
to change the target for a possible existing inflight interrupt, see
vgic_migrate_irq. We need to handle both the case where the vLPI is
inflight but not in an LR yet, which correspond to the
if ( !list_empty(&p->lr_queue) )
case in vgic_migrate_irq. In that case, we remove the struct pending_irq
from lr_queue and inflight of the old vcpu and add it to the list of the
new vcpu. More difficult is the case of a vLPI which is both inflight
and in an LR. In the code it corresponds to:
if ( !list_empty(&p->inflight) )
and we need to set GIC_IRQ_GUEST_MIGRATING. In other words, we need to
call a function that is pretty much like vgic_migrate_irq but without
the irq_set_affinity calls that we cannot handle with LPIs yet. Or you
could just call vgic_migrate_irq making sure that irq_set_affinity does
nothing for LPIs for now.
In the past you replied that vgic_migrate_irq starts with:
if ( p->desc == NULL )
so it wouldn't work for LPIs. Of course, we need to change that check,
but overall the function can be made to work for LPIs as long as
irq_set_affinity does something sensible for them.
If you prefer to implement this after the vgic lock rework, add a TODO
comment, and maybe a BUG_ON(!list_empty(&p->inflight)).
> + spin_unlock_irqrestore(&ovcpu->arch.vgic.lock, flags);
> +
> + /* Now store the new collection in the translation table. */
> + if ( !write_itte_locked(its, devid, eventid, collid, vlpi, &nvcpu) )
> + goto out_unlock;
> +
> + spin_unlock(&its->its_lock);
> +
> + /* TODO: lookup currently-in-guest virtual IRQs and migrate them? */
> +
> + return gicv3_lpi_change_vcpu(its->d, its->doorbell_address,
> + devid, eventid, nvcpu->vcpu_id);
> +
> +out_unlock:
> + spin_unlock(&its->its_lock);
> +
> + return ret;
> +}
> +
> #define ITS_CMD_BUFFER_SIZE(baser) ((((baser) & 0xff) + 1) << 12)
> #define ITS_CMD_OFFSET(reg) ((reg) & GENMASK(19, 5))
>
> @@ -715,6 +768,12 @@ static int vgic_its_handle_cmds(struct domain *d, struct
> virt_its *its)
> case GITS_CMD_MAPTI:
> ret = its_handle_mapti(its, command);
> break;
> + case GITS_CMD_MOVALL:
> + gdprintk(XENLOG_G_INFO, "vGITS: ignoring MOVALL command\n");
> + break;
> + case GITS_CMD_MOVI:
> + ret = its_handle_movi(its, command);
> + break;
> case GITS_CMD_SYNC:
> /* We handle ITS commands synchronously, so we ignore SYNC. */
> break;
> diff --git a/xen/include/asm-arm/gic_v3_its.h
> b/xen/include/asm-arm/gic_v3_its.h
> index 9c08cee..82d788c 100644
> --- a/xen/include/asm-arm/gic_v3_its.h
> +++ b/xen/include/asm-arm/gic_v3_its.h
> @@ -178,8 +178,12 @@ int gicv3_remove_guest_event(struct domain *d, paddr_t
> vdoorbell_address,
> struct pending_irq *gicv3_assign_guest_event(struct domain *d, paddr_t
> doorbell,
> uint32_t devid, uint32_t
> eventid,
> struct vcpu *v, uint32_t
> virt_lpi);
> +int gicv3_lpi_change_vcpu(struct domain *d, paddr_t doorbell,
> + uint32_t devid, uint32_t eventid,
> + unsigned int vcpu_id);
> void gicv3_lpi_update_host_entry(uint32_t host_lpi, int domain_id,
> unsigned int vcpu_id, uint32_t virt_lpi);
> +int gicv3_lpi_update_host_vcpuid(uint32_t host_lpi, unsigned int vcpu_id);
>
> #else
>
> --
> 2.9.0
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> https://lists.xen.org/xen-devel
>
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