linux-kernel - Re: [PATCH v4 5/7] PCI: hv: Use hv_setup

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Message-ID: <e823efbd-892b-45c6-a747-9a7dc1caf48c@linux.microsoft.com>
Date: Mon, 28 Jul 2025 10:12:09 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: mhklinux@...look.com, kys@...rosoft.com, haiyangz@...rosoft.com,
 wei.liu@...nel.org, decui@...rosoft.com, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
 lpieralisi@...nel.org, kw@...ux.com, mani@...nel.org, robh@...nel.org,
 bhelgaas@...gle.com, arnd@...db.de
Cc: x86@...nel.org, linux-hyperv@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-arch@...r.kernel.org
Subject: Re: [PATCH v4 5/7] PCI: hv: Use hv_setup_*() to set up hypercall
 arguments

On 7/17/2025 9:55 PM, mhkelley58@...il.com wrote:
> From: Michael Kelley <mhklinux@...look.com>
> 
> Update hypercall call sites to use the new hv_setup_*() functions
> to set up hypercall arguments. Since these functions zero the
> fixed portion of input memory, remove now redundant calls to memset().
> 
> Signed-off-by: Michael Kelley <mhklinux@...look.com>
> Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
> 
> Notes:
>     Changes in v4:
>     * Rename hv_hvcall_*() functions to hv_setup_*() [Easwar Hariharan]
>     * Rename hv_hvcall_in_batch_size() to hv_get_input_batch_size()
>       [Easwar Hariharan]
>     
>     Changes in v3:
>     * Removed change to definition of struct hv_mmio_write_input so it remains
>       consistent with original Hyper-V definitions. Adjusted argument to
>       hv_hvcall_in_array() accordingly so that the 64 byte 'data' array is
>       not zero'ed. [Nuno Das Neves]
>     
>     Changes in v2:
>     * In hv_arch_irq_unmask(), added check of the number of computed banks
>       in the hv_vpset against the batch_size. Since an hv_vpset currently
>       represents a maximum of 4096 CPUs, the hv_vpset size does not exceed
>       512 bytes and there should always be sufficent space. But do the
>       check just in case something changes. [Nuno Das Neves]
> 
>  drivers/pci/controller/pci-hyperv.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index d2b7e8ea710b..79de85d1d68b 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -620,7 +620,7 @@ static void hv_irq_retarget_interrupt(struct irq_data *data)
>  	struct pci_dev *pdev;
>  	unsigned long flags;
>  	u32 var_size = 0;
> -	int cpu, nr_bank;
> +	int cpu, nr_bank, batch_size;
>  	u64 res;
>  
>  	dest = irq_data_get_effective_affinity_mask(data);
> @@ -636,8 +636,8 @@ static void hv_irq_retarget_interrupt(struct irq_data *data)
>  
>  	local_irq_save(flags);
>  
> -	params = *this_cpu_ptr(hyperv_pcpu_input_arg);
> -	memset(params, 0, sizeof(*params));
> +	batch_size = hv_setup_in_array(&params, sizeof(*params),
> +					sizeof(params->int_target.vp_set.bank_contents[0]));
>  	params->partition_id = HV_PARTITION_ID_SELF;
>  	params->int_entry.source = HV_INTERRUPT_SOURCE_MSI;
>  	params->int_entry.msi_entry.address.as_uint32 = int_desc->address & 0xffffffff;
> @@ -669,7 +669,7 @@ static void hv_irq_retarget_interrupt(struct irq_data *data)
>  		nr_bank = cpumask_to_vpset(&params->int_target.vp_set, tmp);
>  		free_cpumask_var(tmp);
>  
> -		if (nr_bank <= 0) {
> +		if (nr_bank <= 0 || nr_bank > batch_size) {
>  			res = 1;
>  			goto out;
>  		}
> @@ -1102,11 +1102,9 @@ static void hv_pci_read_mmio(struct device *dev, phys_addr_t gpa, int size, u32
>  
>  	/*
>  	 * 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.
> +	 * to use the per-cpu argument page.
>  	 */
> -	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
> -	out = *this_cpu_ptr(hyperv_pcpu_input_arg) + sizeof(*in);
> +	hv_setup_inout(&in, sizeof(*in), &out, sizeof(*out));
>  	in->gpa = gpa;
>  	in->size = size;
>  
> @@ -1135,9 +1133,9 @@ static void hv_pci_write_mmio(struct device *dev, phys_addr_t gpa, int size, u32
>  
>  	/*
>  	 * Must be called with interrupts disabled so it is safe
> -	 * to use the per-cpu input argument memory.
> +	 * to use the per-cpu argument page.
>  	 */
> -	in = *this_cpu_ptr(hyperv_pcpu_input_arg);
> +	hv_setup_in_array(&in, offsetof(typeof(*in), data), sizeof(in->data[0]));
>  	in->gpa = gpa;
>  	in->size = size;
>  	switch (size) {

Reviewed-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>