Subject: Re: [PATCH 5/8] powerpc: add real mode support for dma operations on powernv

From: Alexey Kardashevskiy <[email-masked]>
Date: Wed, 10 Jul 2013 13:17:19 +1000

On 07/10/2013 02:02 AM, Alexander Graf wrote:
> On 07/06/2013 05:07 PM, Alexey Kardashevskiy wrote:
>> The existing TCE machine calls (tce_build and tce_free) only support
>> virtual mode as they call __raw_writeq for TCE invalidation what
>> fails in real mode.
>>
>> This introduces tce_build_rm and tce_free_rm real mode versions
>> which do mostly the same but use "Store Doubleword Caching Inhibited
>> Indexed" instruction for TCE invalidation.
> 
> So would always using stdcix have any bad side effects?

PowerISA says "They must be executed only when MSRDR=0" about stdcix.

> 
> 
> Alex
> 
>>
>> This new feature is going to be utilized by real mode support of VFIO.
>>
>> Signed-off-by: Alexey Kardashevskiy<[email-masked]>
>> ---
>>   arch/powerpc/include/asm/machdep.h        | 12 ++++++++++
>>   arch/powerpc/platforms/powernv/pci-ioda.c | 26 +++++++++++++++------
>>   arch/powerpc/platforms/powernv/pci.c      | 38
>> ++++++++++++++++++++++++++-----
>>   arch/powerpc/platforms/powernv/pci.h      |  2 +-
>>   4 files changed, 64 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/machdep.h
>> b/arch/powerpc/include/asm/machdep.h
>> index 92386fc..0c19eef 100644
>> --- a/arch/powerpc/include/asm/machdep.h
>> +++ b/arch/powerpc/include/asm/machdep.h
>> @@ -75,6 +75,18 @@ struct machdep_calls {
>>                       long index);
>>       void        (*tce_flush)(struct iommu_table *tbl);
>>
>> +    /* _rm versions are for real mode use only */
>> +    int        (*tce_build_rm)(struct iommu_table *tbl,
>> +                     long index,
>> +                     long npages,
>> +                     unsigned long uaddr,
>> +                     enum dma_data_direction direction,
>> +                     struct dma_attrs *attrs);
>> +    void        (*tce_free_rm)(struct iommu_table *tbl,
>> +                    long index,
>> +                    long npages);
>> +    void        (*tce_flush_rm)(struct iommu_table *tbl);
>> +
>>       void __iomem *    (*ioremap)(phys_addr_t addr, unsigned long size,
>>                      unsigned long flags, void *caller);
>>       void        (*iounmap)(volatile void __iomem *token);
>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c
>> b/arch/powerpc/platforms/powernv/pci-ioda.c
>> index 2931d97..2797dec 100644
>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>> @@ -68,6 +68,12 @@ define_pe_printk_level(pe_err, KERN_ERR);
>>   define_pe_printk_level(pe_warn, KERN_WARNING);
>>   define_pe_printk_level(pe_info, KERN_INFO);
>>
>> +static inline void rm_writed(unsigned long paddr, u64 val)
>> +{
>> +    __asm__ __volatile__("sync; stdcix %0,0,%1"
>> +        : : "r" (val), "r" (paddr) : "memory");
>> +}
>> +
>>   static int pnv_ioda_alloc_pe(struct pnv_phb *phb)
>>   {
>>       unsigned long pe;
>> @@ -442,7 +448,7 @@ static void pnv_pci_ioda_dma_dev_setup(struct pnv_phb
>> *phb, struct pci_dev *pdev
>>   }
>>
>>   static void pnv_pci_ioda1_tce_invalidate(struct iommu_table *tbl,
>> -                     u64 *startp, u64 *endp)
>> +                     u64 *startp, u64 *endp, bool rm)
>>   {
>>       u64 __iomem *invalidate = (u64 __iomem *)tbl->it_index;
>>       unsigned long start, end, inc;
>> @@ -471,7 +477,10 @@ static void pnv_pci_ioda1_tce_invalidate(struct
>> iommu_table *tbl,
>>
>>           mb(); /* Ensure above stores are visible */
>>           while (start<= end) {
>> -                __raw_writeq(start, invalidate);
>> +        if (rm)
>> +            rm_writed((unsigned long) invalidate, start);
>> +        else
>> +            __raw_writeq(start, invalidate);
>>                   start += inc;
>>           }
>>
>> @@ -483,7 +492,7 @@ static void pnv_pci_ioda1_tce_invalidate(struct
>> iommu_table *tbl,
>>
>>   static void pnv_pci_ioda2_tce_invalidate(struct pnv_ioda_pe *pe,
>>                        struct iommu_table *tbl,
>> -                     u64 *startp, u64 *endp)
>> +                     u64 *startp, u64 *endp, bool rm)
>>   {
>>       unsigned long start, end, inc;
>>       u64 __iomem *invalidate = (u64 __iomem *)tbl->it_index;
>> @@ -502,22 +511,25 @@ static void pnv_pci_ioda2_tce_invalidate(struct
>> pnv_ioda_pe *pe,
>>       mb();
>>
>>       while (start<= end) {
>> -        __raw_writeq(start, invalidate);
>> +        if (rm)
>> +            rm_writed((unsigned long) invalidate, start);
>> +        else
>> +            __raw_writeq(start, invalidate);
>>           start += inc;
>>       }
>>   }
>>
>>   void pnv_pci_ioda_tce_invalidate(struct iommu_table *tbl,
>> -                 u64 *startp, u64 *endp)
>> +                 u64 *startp, u64 *endp, bool rm)
>>   {
>>       struct pnv_ioda_pe *pe = container_of(tbl, struct pnv_ioda_pe,
>>                             tce32_table);
>>       struct pnv_phb *phb = pe->phb;
>>
>>       if (phb->type == PNV_PHB_IODA1)
>> -        pnv_pci_ioda1_tce_invalidate(tbl, startp, endp);
>> +        pnv_pci_ioda1_tce_invalidate(tbl, startp, endp, rm);
>>       else
>> -        pnv_pci_ioda2_tce_invalidate(pe, tbl, startp, endp);
>> +        pnv_pci_ioda2_tce_invalidate(pe, tbl, startp, endp, rm);
>>   }
>>
>>   static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
>> diff --git a/arch/powerpc/platforms/powernv/pci.c
>> b/arch/powerpc/platforms/powernv/pci.c
>> index e16b729..280f614 100644
>> --- a/arch/powerpc/platforms/powernv/pci.c
>> +++ b/arch/powerpc/platforms/powernv/pci.c
>> @@ -336,7 +336,7 @@ struct pci_ops pnv_pci_ops = {
>>
>>   static int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
>>                unsigned long uaddr, enum dma_data_direction direction,
>> -             struct dma_attrs *attrs)
>> +             struct dma_attrs *attrs, bool rm)
>>   {
>>       u64 proto_tce;
>>       u64 *tcep, *tces;
>> @@ -358,12 +358,19 @@ static int pnv_tce_build(struct iommu_table *tbl,
>> long index, long npages,
>>        * of flags if that becomes the case
>>        */
>>       if (tbl->it_type&  TCE_PCI_SWINV_CREATE)
>> -        pnv_pci_ioda_tce_invalidate(tbl, tces, tcep - 1);
>> +        pnv_pci_ioda_tce_invalidate(tbl, tces, tcep - 1, rm);
>>
>>       return 0;
>>   }
>>
>> -static void pnv_tce_free(struct iommu_table *tbl, long index, long npages)
>> +static int pnv_tce_build_vm(struct iommu_table *tbl, long index, long
>> npages,
>> +                unsigned long uaddr, enum dma_data_direction direction,
>> +                struct dma_attrs *attrs)
>> +{
>> +    return pnv_tce_build(tbl, index, npages, uaddr, direction, attrs,
>> false);
>> +}
>> +
>> +static void pnv_tce_free(struct iommu_table *tbl, long index, long
>> npages, bool rm)
>>   {
>>       u64 *tcep, *tces;
>>
>> @@ -373,7 +380,12 @@ static void pnv_tce_free(struct iommu_table *tbl,
>> long index, long npages)
>>           *(tcep++) = 0;
>>
>>       if (tbl->it_type&  TCE_PCI_SWINV_FREE)
>> -        pnv_pci_ioda_tce_invalidate(tbl, tces, tcep - 1);
>> +        pnv_pci_ioda_tce_invalidate(tbl, tces, tcep - 1, rm);
>> +}
>> +
>> +static void pnv_tce_free_vm(struct iommu_table *tbl, long index, long
>> npages)
>> +{
>> +    pnv_tce_free(tbl, index, npages, false);
>>   }
>>
>>   static unsigned long pnv_tce_get(struct iommu_table *tbl, long index)
>> @@ -381,6 +393,18 @@ static unsigned long pnv_tce_get(struct iommu_table
>> *tbl, long index)
>>       return ((u64 *)tbl->it_base)[index - tbl->it_offset];
>>   }
>>
>> +static int pnv_tce_build_rm(struct iommu_table *tbl, long index, long
>> npages,
>> +                unsigned long uaddr, enum dma_data_direction direction,
>> +                struct dma_attrs *attrs)
>> +{
>> +    return pnv_tce_build(tbl, index, npages, uaddr, direction, attrs,
>> true);
>> +}
>> +
>> +static void pnv_tce_free_rm(struct iommu_table *tbl, long index, long
>> npages)
>> +{
>> +    pnv_tce_free(tbl, index, npages, true);
>> +}
>> +
>>   void pnv_pci_setup_iommu_table(struct iommu_table *tbl,
>>                      void *tce_mem, u64 tce_size,
>>                      u64 dma_offset)
>> @@ -545,8 +569,10 @@ void __init pnv_pci_init(void)
>>
>>       /* Configure IOMMU DMA hooks */
>>       ppc_md.pci_dma_dev_setup = pnv_pci_dma_dev_setup;
>> -    ppc_md.tce_build = pnv_tce_build;
>> -    ppc_md.tce_free = pnv_tce_free;
>> +    ppc_md.tce_build = pnv_tce_build_vm;
>> +    ppc_md.tce_free = pnv_tce_free_vm;
>> +    ppc_md.tce_build_rm = pnv_tce_build_rm;
>> +    ppc_md.tce_free_rm = pnv_tce_free_rm;
>>       ppc_md.tce_get = pnv_tce_get;
>>       ppc_md.pci_probe_mode = pnv_pci_probe_mode;
>>       set_pci_dma_ops(&dma_iommu_ops);
>> diff --git a/arch/powerpc/platforms/powernv/pci.h
>> b/arch/powerpc/platforms/powernv/pci.h
>> index 25d76c4..6799374 100644
>> --- a/arch/powerpc/platforms/powernv/pci.h
>> +++ b/arch/powerpc/platforms/powernv/pci.h
>> @@ -158,6 +158,6 @@ extern void pnv_pci_init_p5ioc2_hub(struct
>> device_node *np);
>>   extern void pnv_pci_init_ioda_hub(struct device_node *np);
>>   extern void pnv_pci_init_ioda2_phb(struct device_node *np);
>>   extern void pnv_pci_ioda_tce_invalidate(struct iommu_table *tbl,
>> -                    u64 *startp, u64 *endp);
>> +                    u64 *startp, u64 *endp, bool rm);
>>
>>   #endif /* __POWERNV_PCI_H */
> 

-- 
Alexey