Re: [PATCH v2 3/3] PCI: hv: Introduce hv_msi_entry

Andrew Murray
2020-02-03T09:51:46Z

On Mon, Feb 03, 2020 at 01:03:13PM +0800, Boqun Feng wrote:
> Add a new structure (hv_msi_entry), which is also defined int tlfs, to

s/int/in the/ ?

> describe the msi entry for HVCALL_RETARGET_INTERRUPT. The structure is
> needed because its layout may be different from architecture to
> architecture.
>
> Also add a new generic interface hv_set_msi_address_from_desc() to allow
> different archs to set the msi address from msi_desc.
>
> No functional change, only preparation for the future support of virtual
> PCI on non-x86 architectures.
>
> Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
> ---
> arch/x86/include/asm/hyperv-tlfs.h | 11 +++++++++--
> arch/x86/include/asm/mshyperv.h | 5 +++++
> drivers/pci/controller/pci-hyperv.c | 4 ++--
> 3 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 4a76e442481a..953b3ad38746 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -912,11 +912,18 @@ struct hv_partition_assist_pg {
> u32 tlb_lock_count;
> };
>
> +union hv_msi_entry {
> + u64 as_uint64;
> + struct {
> + u32 address;
> + u32 data;
> + } __packed;
> +};
> +
> struct hv_interrupt_entry {
> u32 source; /* 1 for MSI(-X) */
> u32 reserved1;
> - u32 address;
> - u32 data;
> + union hv_msi_entry msi_entry;
> } __packed;
>
> /*
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 6b79515abb82..3bdaa3b6e68f 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -240,6 +240,11 @@ bool hv_vcpu_is_preempted(int vcpu);
> static inline void hv_apic_init(void) {}
> #endif
>
> +#define hv_set_msi_address_from_desc(msi_entry, msi_desc) \
> +do { \
> + (msi_entry)->address = (msi_desc)->msg.address_lo; \
> +} while (0)

Given that this is a single statement, is there really a need for the do ; while(0) ?

> +
> #else /* CONFIG_HYPERV */
> static inline void hyperv_init(void) {}
> static inline void hyperv_setup_mmu_ops(void) {}
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 0d9b74503577..2240f2b3643e 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1170,8 +1170,8 @@ static void hv_irq_unmask(struct irq_data *data)
> memset(params, 0, sizeof(*params));
> params->partition_id = HV_PARTITION_ID_SELF;
> params->int_entry.source = 1; /* MSI(-X) */
> - params->int_entry.address = msi_desc->msg.address_lo;
> - params->int_entry.data = msi_desc->msg.data;
> + hv_set_msi_address_from_desc(&params->int_entry.msi_entry, msi_desc);
> + params->int_entry.msi_entry.data = msi_desc->msg.data;

If the layout may differ, then don't we also need a wrapper for data?

Thanks,

Andrew Murray

> params->device_id = (hbus->hdev->dev_instance.b[5] << 24) |
> (hbus->hdev->dev_instance.b[4] << 16) |
> (hbus->hdev->dev_instance.b[7] << 8) |
> --
> 2.24.1
>