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Message-ID: <20200212023540-mutt-send-email-mst@kernel.org>
Date: Wed, 12 Feb 2020 02:40:03 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Zha Bin <zhabin@...ux.alibaba.com>
Cc: linux-kernel@...r.kernel.org, jasowang@...hat.com, slp@...hat.com,
virtio-dev@...ts.oasis-open.org, qemu-devel@...gnu.org,
gerry@...ux.alibaba.com, jing2.liu@...ux.intel.com,
chao.p.peng@...ux.intel.com
Subject: Re: [PATCH v2 3/5] virtio-mmio: create a generic MSI irq domain
On Mon, Feb 10, 2020 at 05:05:19PM +0800, Zha Bin wrote:
> From: Liu Jiang <gerry@...ux.alibaba.com>
>
> Create a generic irq domain for all architectures which
> supports virtio-mmio. The device offering VIRTIO_F_MMIO_MSI
> feature bit can use this irq domain.
>
> Signed-off-by: Liu Jiang <gerry@...ux.alibaba.com>
> Co-developed-by: Zha Bin <zhabin@...ux.alibaba.com>
> Signed-off-by: Zha Bin <zhabin@...ux.alibaba.com>
> Co-developed-by: Jing Liu <jing2.liu@...ux.intel.com>
> Signed-off-by: Jing Liu <jing2.liu@...ux.intel.com>
> Co-developed-by: Chao Peng <chao.p.peng@...ux.intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@...ux.intel.com>
> ---
> drivers/base/platform-msi.c | 4 +-
> drivers/virtio/Kconfig | 9 ++++
> drivers/virtio/virtio_mmio_msi.h | 93 ++++++++++++++++++++++++++++++++++++++++
> include/linux/msi.h | 1 +
> 4 files changed, 105 insertions(+), 2 deletions(-)
> create mode 100644 drivers/virtio/virtio_mmio_msi.h
>
> diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c
> index 8da314b..45752f1 100644
> --- a/drivers/base/platform-msi.c
> +++ b/drivers/base/platform-msi.c
> @@ -31,12 +31,11 @@ struct platform_msi_priv_data {
> /* The devid allocator */
> static DEFINE_IDA(platform_msi_devid_ida);
>
> -#ifdef GENERIC_MSI_DOMAIN_OPS
> /*
> * Convert an msi_desc to a globaly unique identifier (per-device
> * devid + msi_desc position in the msi_list).
> */
> -static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
> +irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
> {
> u32 devid;
>
> @@ -45,6 +44,7 @@ static irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc)
> return (devid << (32 - DEV_ID_SHIFT)) | desc->platform.msi_index;
> }
>
> +#ifdef GENERIC_MSI_DOMAIN_OPS
> static void platform_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
> {
> arg->desc = desc;
> diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
> index 078615c..551a9f7 100644
> --- a/drivers/virtio/Kconfig
> +++ b/drivers/virtio/Kconfig
> @@ -84,6 +84,15 @@ config VIRTIO_MMIO
>
> If unsure, say N.
>
> +config VIRTIO_MMIO_MSI
> + bool "Memory-mapped virtio device MSI"
> + depends on VIRTIO_MMIO && GENERIC_MSI_IRQ_DOMAIN && GENERIC_MSI_IRQ
> + help
> + This allows device drivers to support msi interrupt handling for
> + virtio-mmio devices. It can improve performance greatly.
> +
> + If unsure, say N.
> +
> config VIRTIO_MMIO_CMDLINE_DEVICES
> bool "Memory mapped virtio devices parameter parsing"
> depends on VIRTIO_MMIO
> diff --git a/drivers/virtio/virtio_mmio_msi.h b/drivers/virtio/virtio_mmio_msi.h
> new file mode 100644
> index 0000000..27cb2af
> --- /dev/null
> +++ b/drivers/virtio/virtio_mmio_msi.h
> @@ -0,0 +1,93 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef _DRIVERS_VIRTIO_VIRTIO_MMIO_MSI_H
> +#define _DRIVERS_VIRTIO_VIRTIO_MMIO_MSI_H
> +
> +#ifdef CONFIG_VIRTIO_MMIO_MSI
> +
> +#include <linux/msi.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/platform_device.h>
> +
> +static irq_hw_number_t mmio_msi_hwirq;
> +static struct irq_domain *mmio_msi_domain;
So each instance of including this header will create its own
copy of the variables. That won't do the right thing.
> +
> +struct irq_domain *__weak arch_msi_root_irq_domain(void)
> +{
> + return NULL;
> +}
> +
> +void __weak irq_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +}
> +
> +static void mmio_msi_mask_irq(struct irq_data *data)
> +{
> +}
> +
> +static void mmio_msi_unmask_irq(struct irq_data *data)
> +{
> +}
> +
> +static struct irq_chip mmio_msi_controller = {
> + .name = "VIRTIO-MMIO-MSI",
> + .irq_mask = mmio_msi_mask_irq,
> + .irq_unmask = mmio_msi_unmask_irq,
> + .irq_ack = irq_chip_ack_parent,
> + .irq_retrigger = irq_chip_retrigger_hierarchy,
> + .irq_compose_msi_msg = irq_msi_compose_msg,
> + .flags = IRQCHIP_SKIP_SET_WAKE,
> +};
> +
> +static int mmio_msi_prepare(struct irq_domain *domain, struct device *dev,
> + int nvec, msi_alloc_info_t *arg)
> +{
> + memset(arg, 0, sizeof(*arg));
> + return 0;
> +}
> +
> +static void mmio_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
> +{
> + mmio_msi_hwirq = platform_msi_calc_hwirq(desc);
> +}
> +
> +static irq_hw_number_t mmio_msi_get_hwirq(struct msi_domain_info *info,
> + msi_alloc_info_t *arg)
> +{
> + return mmio_msi_hwirq;
> +}
> +
> +static struct msi_domain_ops mmio_msi_domain_ops = {
> + .msi_prepare = mmio_msi_prepare,
> + .set_desc = mmio_msi_set_desc,
> + .get_hwirq = mmio_msi_get_hwirq,
> +};
> +
> +static struct msi_domain_info mmio_msi_domain_info = {
> + .flags = MSI_FLAG_USE_DEF_DOM_OPS |
> + MSI_FLAG_USE_DEF_CHIP_OPS |
> + MSI_FLAG_ACTIVATE_EARLY,
> + .ops = &mmio_msi_domain_ops,
> + .chip = &mmio_msi_controller,
> + .handler = handle_edge_irq,
> + .handler_name = "edge",
> +};
> +
> +static inline void mmio_msi_create_irq_domain(void)
> +{
> + struct fwnode_handle *fn;
> + struct irq_domain *parent = arch_msi_root_irq_domain();
> +
> + fn = irq_domain_alloc_named_fwnode("VIRTIO-MMIO-MSI");
> + if (fn && parent) {
> + mmio_msi_domain =
> + platform_msi_create_irq_domain(fn,
> + &mmio_msi_domain_info, parent);
> + irq_domain_free_fwnode(fn);
> + }
> +}
It does not look like anyone cleans up this domain.
So how does this work with a modular virtio mmio?
what happens when you unload the module?
> +#else
> +static inline void mmio_msi_create_irq_domain(void) {}
> +#endif
> +
> +#endif
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 8ad679e..ee5f566 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -362,6 +362,7 @@ int platform_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq,
> unsigned int nvec);
> void *platform_msi_get_host_data(struct irq_domain *domain);
> +irq_hw_number_t platform_msi_calc_hwirq(struct msi_desc *desc);
> #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */
>
> #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
> --
> 1.8.3.1
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