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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH V3 18/23] xen/dm: Introduce xendevicemodel_set_irq_level DM op
On Mon, 30 Nov 2020, Oleksandr Tyshchenko wrote:
> From: Julien Grall <julien.grall@xxxxxxx>
>
> This patch adds ability to the device emulator to notify otherend
> (some entity running in the guest) using a SPI and implements Arm
> specific bits for it. Proposed interface allows emulator to set
> the logical level of a one of a domain's IRQ lines.
>
> We can't reuse the existing DM op (xen_dm_op_set_isa_irq_level)
> to inject an interrupt as the "isa_irq" field is only 8-bit and
> able to cover IRQ 0 - 255, whereas we need a wider range (0 - 1020).
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
>
> ---
> Please note, this is a split/cleanup/hardening of Julien's PoC:
> "Add support for Guest IO forwarding to a device emulator"
>
> ***
> Please note, I left interface untouched since there is still
> an open discussion what interface to use/what information to pass
> to the hypervisor. The question whether we should abstract away
> the state of the line or not.
> ***
Let's start with a simple question: is this going to work with
virtio-mmio emulation in QEMU that doesn't lower the state of the line
to end the notification (only calls qemu_set_irq(irq, high))?
See: hw/virtio/virtio-mmio.c:virtio_mmio_update_irq
Alex (CC'ed) might be able to confirm whether I am reading the QEMU code
correctly. Assuming that it is true that QEMU is only raising the level,
never lowering it, although the emulation is obviously not correct, I
would rather keep QEMU as is for efficiency reasons, and because we
don't want to deviate from the common implementation in QEMU.
Looking at this patch and at vgic_inject_irq, yes, I think it would
work as is.
So it looks like we are going to end up with an interface that:
- in theory it is modelling the line closely
- in practice it is only called to "trigger the IRQ"
Hence my preference for being explicit about it and just call it
trigger_irq.
If we keep the patch as is, should we at least add a comment to document
the "QEMU style" use model?
> Changes RFC -> V1:
> - check incoming parameters in arch_dm_op()
> - add explicit padding to struct xen_dm_op_set_irq_level
>
> Changes V1 -> V2:
> - update the author of a patch
> - update patch description
> - check that padding is always 0
> - mention that interface is Arm only and only SPIs are
> supported for now
> - allow to set the logical level of a line for non-allocated
> interrupts only
> - add xen_dm_op_set_irq_level_t
>
> Changes V2 -> V3:
> - no changes
> ---
> ---
> tools/include/xendevicemodel.h | 4 ++
> tools/libs/devicemodel/core.c | 18 +++++++++
> tools/libs/devicemodel/libxendevicemodel.map | 1 +
> xen/arch/arm/dm.c | 57
> +++++++++++++++++++++++++++-
> xen/common/dm.c | 1 +
> xen/include/public/hvm/dm_op.h | 16 ++++++++
> 6 files changed, 96 insertions(+), 1 deletion(-)
>
> diff --git a/tools/include/xendevicemodel.h b/tools/include/xendevicemodel.h
> index e877f5c..c06b3c8 100644
> --- a/tools/include/xendevicemodel.h
> +++ b/tools/include/xendevicemodel.h
> @@ -209,6 +209,10 @@ int xendevicemodel_set_isa_irq_level(
> xendevicemodel_handle *dmod, domid_t domid, uint8_t irq,
> unsigned int level);
>
> +int xendevicemodel_set_irq_level(
> + xendevicemodel_handle *dmod, domid_t domid, unsigned int irq,
> + unsigned int level);
> +
> /**
> * This function maps a PCI INTx line to a an IRQ line.
> *
> diff --git a/tools/libs/devicemodel/core.c b/tools/libs/devicemodel/core.c
> index 4d40639..30bd79f 100644
> --- a/tools/libs/devicemodel/core.c
> +++ b/tools/libs/devicemodel/core.c
> @@ -430,6 +430,24 @@ int xendevicemodel_set_isa_irq_level(
> return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op));
> }
>
> +int xendevicemodel_set_irq_level(
> + xendevicemodel_handle *dmod, domid_t domid, uint32_t irq,
> + unsigned int level)
> +{
> + struct xen_dm_op op;
> + struct xen_dm_op_set_irq_level *data;
> +
> + memset(&op, 0, sizeof(op));
> +
> + op.op = XEN_DMOP_set_irq_level;
> + data = &op.u.set_irq_level;
> +
> + data->irq = irq;
> + data->level = level;
> +
> + return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op));
> +}
> +
> int xendevicemodel_set_pci_link_route(
> xendevicemodel_handle *dmod, domid_t domid, uint8_t link, uint8_t irq)
> {
> diff --git a/tools/libs/devicemodel/libxendevicemodel.map
> b/tools/libs/devicemodel/libxendevicemodel.map
> index 561c62d..a0c3012 100644
> --- a/tools/libs/devicemodel/libxendevicemodel.map
> +++ b/tools/libs/devicemodel/libxendevicemodel.map
> @@ -32,6 +32,7 @@ VERS_1.2 {
> global:
> xendevicemodel_relocate_memory;
> xendevicemodel_pin_memory_cacheattr;
> + xendevicemodel_set_irq_level;
> } VERS_1.1;
>
> VERS_1.3 {
> diff --git a/xen/arch/arm/dm.c b/xen/arch/arm/dm.c
> index 5d3da37..e4bb233 100644
> --- a/xen/arch/arm/dm.c
> +++ b/xen/arch/arm/dm.c
> @@ -17,10 +17,65 @@
> #include <xen/dm.h>
> #include <xen/hypercall.h>
>
> +#include <asm/vgic.h>
> +
> int arch_dm_op(struct xen_dm_op *op, struct domain *d,
> const struct dmop_args *op_args, bool *const_op)
> {
> - return -EOPNOTSUPP;
> + int rc;
> +
> + switch ( op->op )
> + {
> + case XEN_DMOP_set_irq_level:
> + {
> + const struct xen_dm_op_set_irq_level *data =
> + &op->u.set_irq_level;
> + unsigned int i;
> +
> + /* Only SPIs are supported */
> + if ( (data->irq < NR_LOCAL_IRQS) || (data->irq >= vgic_num_irqs(d)) )
> + {
> + rc = -EINVAL;
> + break;
> + }
> +
> + if ( data->level != 0 && data->level != 1 )
> + {
> + rc = -EINVAL;
> + break;
> + }
> +
> + /* Check that padding is always 0 */
> + for ( i = 0; i < sizeof(data->pad); i++ )
> + {
> + if ( data->pad[i] )
> + {
> + rc = -EINVAL;
> + break;
> + }
> + }
> +
> + /*
> + * Allow to set the logical level of a line for non-allocated
> + * interrupts only.
> + */
> + if ( test_bit(data->irq, d->arch.vgic.allocated_irqs) )
> + {
> + rc = -EINVAL;
> + break;
> + }
> +
> + vgic_inject_irq(d, NULL, data->irq, data->level);
> + rc = 0;
> + break;
> + }
> +
> + default:
> + rc = -EOPNOTSUPP;
> + break;
> + }
> +
> + return rc;
> }
>
> /*
> diff --git a/xen/common/dm.c b/xen/common/dm.c
> index 9d394fc..7bfb46c 100644
> --- a/xen/common/dm.c
> +++ b/xen/common/dm.c
> @@ -48,6 +48,7 @@ static int dm_op(const struct dmop_args *op_args)
> [XEN_DMOP_remote_shutdown] = sizeof(struct
> xen_dm_op_remote_shutdown),
> [XEN_DMOP_relocate_memory] = sizeof(struct
> xen_dm_op_relocate_memory),
> [XEN_DMOP_pin_memory_cacheattr] = sizeof(struct
> xen_dm_op_pin_memory_cacheattr),
> + [XEN_DMOP_set_irq_level] = sizeof(struct
> xen_dm_op_set_irq_level),
> };
>
> rc = rcu_lock_remote_domain_by_id(op_args->domid, &d);
> diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h
> index 66cae1a..1f70d58 100644
> --- a/xen/include/public/hvm/dm_op.h
> +++ b/xen/include/public/hvm/dm_op.h
> @@ -434,6 +434,21 @@ struct xen_dm_op_pin_memory_cacheattr {
> };
> typedef struct xen_dm_op_pin_memory_cacheattr
> xen_dm_op_pin_memory_cacheattr_t;
>
> +/*
> + * XEN_DMOP_set_irq_level: Set the logical level of a one of a domain's
> + * IRQ lines (currently Arm only).
> + * Only SPIs are supported.
> + */
> +#define XEN_DMOP_set_irq_level 19
> +
> +struct xen_dm_op_set_irq_level {
> + uint32_t irq;
> + /* IN - Level: 0 -> deasserted, 1 -> asserted */
> + uint8_t level;
> + uint8_t pad[3];
> +};
> +typedef struct xen_dm_op_set_irq_level xen_dm_op_set_irq_level_t;
> +
> struct xen_dm_op {
> uint32_t op;
> uint32_t pad;
> @@ -447,6 +462,7 @@ struct xen_dm_op {
> xen_dm_op_track_dirty_vram_t track_dirty_vram;
> xen_dm_op_set_pci_intx_level_t set_pci_intx_level;
> xen_dm_op_set_isa_irq_level_t set_isa_irq_level;
> + xen_dm_op_set_irq_level_t set_irq_level;
> xen_dm_op_set_pci_link_route_t set_pci_link_route;
> xen_dm_op_modified_memory_t modified_memory;
> xen_dm_op_set_mem_type_t set_mem_type;
> --
> 2.7.4
>
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