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SubjectRe: [PATCH v3 1/2] PCI: hv: Replace hv_vp_set with hv_vpset
On Wed, Feb 27, 2019 at 04:53:37PM +0100, Vitaly Kuznetsov wrote:
> Maya Nakamura <m.maya.nakamura@gmail.com> writes:
>
> > Remove a duplicate definition of VP set (hv_vp_set) and use the common
> > definition (hv_vpset) that is used in other places.
> >
> > Change the order of the members in struct hv_pcibus_device so that the
> > declaration of retarget_msi_interrupt_params is the last member. Struct
> > hv_vpset, which contains a flexible array, is nested two levels deep in
> > struct hv_pcibus_device via retarget_msi_interrupt_params.
> >
> > Add a comment that retarget_msi_interrupt_params should be the last member
> > of struct hv_pcibus_device.
> >
> > Signed-off-by: Maya Nakamura <m.maya.nakamura@gmail.com>
> > ---
> > Change in v3:
> > - Correct the v2 change log.
> >
> > Change in v2:
> > - Update the commit message.
> >
> > drivers/pci/controller/pci-hyperv.c | 25 ++++++++++++-------------
> > 1 file changed, 12 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index 9ba4d12c179c..da8b58d8630d 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -393,12 +393,6 @@ struct hv_interrupt_entry {
> >
> > #define HV_VP_SET_BANK_COUNT_MAX 5 /* current implementation limit */
> >
> > -struct hv_vp_set {
> > - u64 format; /* 0 (HvGenericSetSparse4k) */
> > - u64 valid_banks;
> > - u64 masks[HV_VP_SET_BANK_COUNT_MAX];
> > -};
> > -
> > /*
> > * flags for hv_device_interrupt_target.flags
> > */
> > @@ -410,7 +404,7 @@ struct hv_device_interrupt_target {
> > u32 flags;
> > union {
> > u64 vp_mask;
> > - struct hv_vp_set vp_set;
> > + struct hv_vpset vp_set;
> > };
> > };
> >
> > @@ -460,12 +454,16 @@ struct hv_pcibus_device {
> > struct msi_controller msi_chip;
> > struct irq_domain *irq_domain;
> >
> > - /* hypercall arg, must not cross page boundary */
> > - struct retarget_msi_interrupt retarget_msi_interrupt_params;
> > -
> > spinlock_t retarget_msi_interrupt_lock;
> >
> > struct workqueue_struct *wq;
> > +
> > + /* hypercall arg, must not cross page boundary */
> > + struct retarget_msi_interrupt retarget_msi_interrupt_params;
> > +
>
> One more thing here (and again sorry for being late): this structure is
> being used as Hyper-V hypercall argument and these have special
> requirements on alignment (8 bytes). struct retarget_msi_interrupt is
> packed and depending on your environment/compiler you may or may not see
> the issue but I has able to get HVCALL_RETARGET_INTERRUPT failing with
> the return value of 4 (HV_STATUS_INVALID_ALIGNMENT).
>
> I suggest we add __aligned(8) to 'struct retarget_msi_interrupt'
> definition (I haven't tested this but should work). This is not a new
> issue, it existed before your patch, but the code movement you do may
> change the exposure.

I am happy to apply this small fix _before_ this patch but if you want
me to merge them for v5.1 this must be put together and tested quite
quickly.

For the time being I am not dropping this patch from the PCI queue,
waiting for an update from you guys.

Thanks,
Lorenzo

>
>
> > + /*
> > + * Don't put anything here: retarget_msi_interrupt_params must be last
> > + */
> > };
> >
> > /*
> > @@ -955,12 +953,13 @@ static void hv_irq_unmask(struct irq_data *data)
> > */
> > params->int_target.flags |=
> > HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;
> > - params->int_target.vp_set.valid_banks =
> > + params->int_target.vp_set.valid_bank_mask =
> > (1ull << HV_VP_SET_BANK_COUNT_MAX) - 1;
> >
> > /*
> > * var-sized hypercall, var-size starts after vp_mask (thus
> > - * vp_set.format does not count, but vp_set.valid_banks does).
> > + * vp_set.format does not count, but vp_set.valid_bank_mask
> > + * does).
> > */
> > var_size = 1 + HV_VP_SET_BANK_COUNT_MAX;
> >
> > @@ -974,7 +973,7 @@ static void hv_irq_unmask(struct irq_data *data)
> > goto exit_unlock;
> > }
> >
> > - params->int_target.vp_set.masks[cpu_vmbus / 64] |=
> > + params->int_target.vp_set.bank_contents[cpu_vmbus / 64] |=
> > (1ULL << (cpu_vmbus & 63));
> > }
> > } else {
>
> --
> Vitaly

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