Re: [PATCH v2 2/3] PCI: hv: Move retarget related structures into tlfs header

Andrew Murray
2020-02-03T09:41:24Z

On Mon, Feb 03, 2020 at 01:03:12PM +0800, Boqun Feng wrote:
> Currently, retarget_msi_interrupt and other structures it relys on are
> defined in pci-hyperv.c. However, those structures are actually defined
> in Hypervisor Top-Level Functional Specification [1] and may be
> different in sizes of fields or layout from architecture to
> architecture. Therefore, this patch moves those definitions into x86's

Nit: Rather than 'Therefore, this patch moves ...' - how about 'Let's move
...'?

> tlfs header file to support virtual PCI on non-x86 architectures in the
> future.
>
> Besides, while I'm at it, rename retarget_msi_interrupt to

Nit: 'Besides, while I'm at it' - this type of wording describes what
*you've* done rather than what the patch is doing. You could replace
that quoted text with 'Additionally, '

> hv_retarget_msi_interrupt for the consistent name convention, also

Nit: s/name/naming

> mirroring the name in TLFS.
>
> [1]: https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs
>
> Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
> ---
> arch/x86/include/asm/hyperv-tlfs.h | 31 ++++++++++++++++++++++++++
> drivers/pci/controller/pci-hyperv.c | 34 ++---------------------------
> 2 files changed, 33 insertions(+), 32 deletions(-)
>
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 739bd89226a5..4a76e442481a 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -911,4 +911,35 @@ struct hv_tlb_flush_ex {
> struct hv_partition_assist_pg {
> u32 tlb_lock_count;
> };
> +
> +struct hv_interrupt_entry {
> + u32 source; /* 1 for MSI(-X) */
> + u32 reserved1;
> + u32 address;
> + u32 data;
> +} __packed;

Why have you added __packed here? There is no mention of this change in the
commit log? Is it needed?

> +
> +/*
> + * flags for hv_device_interrupt_target.flags
> + */
> +#define HV_DEVICE_INTERRUPT_TARGET_MULTICAST 1
> +#define HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET 2
> +
> +struct hv_device_interrupt_target {
> + u32 vector;
> + u32 flags;
> + union {
> + u64 vp_mask;
> + struct hv_vpset vp_set;
> + };
> +} __packed;

Same here.

> +
> +/* HvRetargetDeviceInterrupt hypercall */
> +struct hv_retarget_device_interrupt {
> + u64 partition_id;

Why drop the 'self' comment?

> + u64 device_id;
> + struct hv_interrupt_entry int_entry;
> + u64 reserved2;
> + struct hv_device_interrupt_target int_target;
> +} __packed __aligned(8);
> #endif
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index aacfcc90d929..0d9b74503577 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -406,36 +406,6 @@ struct pci_eject_response {
>
> static int pci_ring_size = (4 * PAGE_SIZE);
>
> -struct hv_interrupt_entry {
> - u32 source; /* 1 for MSI(-X) */
> - u32 reserved1;
> - u32 address;
> - u32 data;
> -};
> -
> -/*
> - * flags for hv_device_interrupt_target.flags
> - */
> -#define HV_DEVICE_INTERRUPT_TARGET_MULTICAST 1
> -#define HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET 2
> -
> -struct hv_device_interrupt_target {
> - u32 vector;
> - u32 flags;
> - union {
> - u64 vp_mask;
> - struct hv_vpset vp_set;
> - };
> -};
> -
> -struct retarget_msi_interrupt {
> - u64 partition_id; /* use "self" */
> - u64 device_id;
> - struct hv_interrupt_entry int_entry;
> - u64 reserved2;
> - struct hv_device_interrupt_target int_target;
> -} __packed __aligned(8);
> -
> /*
> * Driver specific state.
> */
> @@ -482,7 +452,7 @@ struct hv_pcibus_device {
> struct workqueue_struct *wq;
>
> /* hypercall arg, must not cross page boundary */
> - struct retarget_msi_interrupt retarget_msi_interrupt_params;
> + struct hv_retarget_device_interrupt retarget_msi_interrupt_params;
>
> /*
> * Don't put anything here: retarget_msi_interrupt_params must be last
> @@ -1178,7 +1148,7 @@ static void hv_irq_unmask(struct irq_data *data)
> {
> struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
> struct irq_cfg *cfg = irqd_cfg(data);
> - struct retarget_msi_interrupt *params;
> + struct hv_retarget_device_interrupt *params;

pci-hyperv.c also makes use of retarget_msi_interrupt_lock - it's really clear
from this name what it protects, however your rename now makes this more
confusing.

Likewise there is a comment in hv_pci_probe that refers to
retarget_msi_interrupt_params which is now stale.

It may be helpful to rename hv_retarget_device_interrupt for consistency with
the docs - however please make sure you catch all the references - I'd suggest
that the move and the rename are in different patches.

Thanks,

Andrew Murray

> struct hv_pcibus_device *hbus;
> struct cpumask *dest;
> cpumask_var_t tmp;
> --
> 2.24.1
>