Re: [Patch v3 13/14] PCI: hv: Add hypercalls to read/write MMIO space

Wei Liu
2022-11-17T15:21:44Z

On Wed, Nov 16, 2022 at 10:41:36AM -0800, Michael Kelley wrote:
[...]
>
> +static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32 *val)
> +{
> + struct hv_mmio_read_input *in;
> + struct hv_mmio_read_output *out;
> + u64 ret;
> +
> + /*
> + * Must be called with interrupts disabled so it is safe
> + * to use the per-cpu input argument page. Use it for
> + * both input and output.
> + */

Perhaps adding something along this line?

WARN_ON(!irqs_disabled());

I can fold this in if you agree.

> + in = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + out = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*in);
> + in->gpa = gpa;
> + in->size = size;
> +
> + ret = hv_do_hypercall(HVCALL_MMIO_READ, in, out);
> + if (hv_result_success(ret)) {
> + switch (size) {
> + case 1:
> + *val = *(u8 *)(out->data);
> + break;
> + case 2:
> + *val = *(u16 *)(out->data);
> + break;
> + default:
> + *val = *(u32 *)(out->data);
> + break;
> + }
> + } else
> + dev_err(dev, "MMIO read hypercall error %llx addr %llx size %d\n",
> + ret, gpa, size);
> +}
> +
> +static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32 val)
> +{
> + struct hv_mmio_write_input *in;
> + u64 ret;
> +
> + /*
> + * Must be called with interrupts disabled so it is safe
> + * to use the per-cpu input argument memory.
> + */

Ditto.

Thanks,
Wei.