linux-kernel - Re: [PATCH v2 13/30] s390/pci: return status from zpci_refresh

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Message-ID: <20220126114505.6ddc8400@p-imbrenda>
Date:   Wed, 26 Jan 2022 11:45:05 +0100
From:   Claudio Imbrenda <imbrenda@...ux.ibm.com>
To:     Matthew Rosato <mjrosato@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, alex.williamson@...hat.com,
        cohuck@...hat.com, schnelle@...ux.ibm.com, farman@...ux.ibm.com,
        pmorel@...ux.ibm.com, borntraeger@...ux.ibm.com, hca@...ux.ibm.com,
        gor@...ux.ibm.com, gerald.schaefer@...ux.ibm.com,
        agordeev@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
        thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/30] s390/pci: return status from
 zpci_refresh_trans

On Fri, 14 Jan 2022 15:31:28 -0500
Matthew Rosato <mjrosato@...ux.ibm.com> wrote:

> Current callers of zpci_refresh_trans don't need to interrogate the status
> returned from the underlying instructions.  However, a subsequent patch
> will add a KVM caller that needs this information.  Add a new argument to
> zpci_refresh_trans to pass the address of a status byte and update
> existing call sites to provide it.
> 
> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>

> ---
>  arch/s390/include/asm/pci_insn.h |  2 +-
>  arch/s390/pci/pci_dma.c          |  6 ++++--
>  arch/s390/pci/pci_insn.c         | 10 +++++-----
>  drivers/iommu/s390-iommu.c       |  4 +++-
>  4 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/s390/include/asm/pci_insn.h b/arch/s390/include/asm/pci_insn.h
> index 5331082fa516..32759c407b8f 100644
> --- a/arch/s390/include/asm/pci_insn.h
> +++ b/arch/s390/include/asm/pci_insn.h
> @@ -135,7 +135,7 @@ union zpci_sic_iib {
>  DECLARE_STATIC_KEY_FALSE(have_mio);
>  
>  u8 zpci_mod_fc(u64 req, struct zpci_fib *fib, u8 *status);
> -int zpci_refresh_trans(u64 fn, u64 addr, u64 range);
> +int zpci_refresh_trans(u64 fn, u64 addr, u64 range, u8 *status);
>  int __zpci_load(u64 *data, u64 req, u64 offset);
>  int zpci_load(u64 *data, const volatile void __iomem *addr, unsigned long len);
>  int __zpci_store(u64 data, u64 req, u64 offset);
> diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
> index a81de48d5ea7..b0a2380bcad8 100644
> --- a/arch/s390/pci/pci_dma.c
> +++ b/arch/s390/pci/pci_dma.c
> @@ -23,8 +23,9 @@ static u32 s390_iommu_aperture_factor = 1;
>  
>  static int zpci_refresh_global(struct zpci_dev *zdev)
>  {
> +	u8 status;
>  	return zpci_refresh_trans((u64) zdev->fh << 32, zdev->start_dma,
> -				  zdev->iommu_pages * PAGE_SIZE);
> +				  zdev->iommu_pages * PAGE_SIZE, &status);
>  }
>  
>  unsigned long *dma_alloc_cpu_table(void)
> @@ -183,6 +184,7 @@ static int __dma_purge_tlb(struct zpci_dev *zdev, dma_addr_t dma_addr,
>  			   size_t size, int flags)
>  {
>  	unsigned long irqflags;
> +	u8 status;
>  	int ret;
>  
>  	/*
> @@ -201,7 +203,7 @@ static int __dma_purge_tlb(struct zpci_dev *zdev, dma_addr_t dma_addr,
>  	}
>  
>  	ret = zpci_refresh_trans((u64) zdev->fh << 32, dma_addr,
> -				 PAGE_ALIGN(size));
> +				 PAGE_ALIGN(size), &status);
>  	if (ret == -ENOMEM && !s390_iommu_strict) {
>  		/* enable the hypervisor to free some resources */
>  		if (zpci_refresh_global(zdev))
> diff --git a/arch/s390/pci/pci_insn.c b/arch/s390/pci/pci_insn.c
> index 0509554301c7..ca6399d52767 100644
> --- a/arch/s390/pci/pci_insn.c
> +++ b/arch/s390/pci/pci_insn.c
> @@ -77,20 +77,20 @@ static inline u8 __rpcit(u64 fn, u64 addr, u64 range, u8 *status)
>  	return cc;
>  }
>  
> -int zpci_refresh_trans(u64 fn, u64 addr, u64 range)
> +int zpci_refresh_trans(u64 fn, u64 addr, u64 range, u8 *status)
>  {
> -	u8 cc, status;
> +	u8 cc;
>  
>  	do {
> -		cc = __rpcit(fn, addr, range, &status);
> +		cc = __rpcit(fn, addr, range, status);
>  		if (cc == 2)
>  			udelay(ZPCI_INSN_BUSY_DELAY);
>  	} while (cc == 2);
>  
>  	if (cc)
> -		zpci_err_insn(cc, status, addr, range);
> +		zpci_err_insn(cc, *status, addr, range);
>  
> -	if (cc == 1 && (status == 4 || status == 16))
> +	if (cc == 1 && (*status == 4 || *status == 16))
>  		return -ENOMEM;
>  
>  	return (cc) ? -EIO : 0;
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index 50860ebdd087..845bb99c183e 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -214,6 +214,7 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
>  	unsigned long irq_flags, nr_pages, i;
>  	unsigned long *entry;
>  	int rc = 0;
> +	u8 status;
>  
>  	if (dma_addr < s390_domain->domain.geometry.aperture_start ||
>  	    dma_addr + size > s390_domain->domain.geometry.aperture_end)
> @@ -238,7 +239,8 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
>  	spin_lock(&s390_domain->list_lock);
>  	list_for_each_entry(domain_device, &s390_domain->devices, list) {
>  		rc = zpci_refresh_trans((u64) domain_device->zdev->fh << 32,
> -					start_dma_addr, nr_pages * PAGE_SIZE);
> +					start_dma_addr, nr_pages * PAGE_SIZE,
> +					&status);
>  		if (rc)
>  			break;
>  	}