Hi Dave,
On 03.06.19 01:12, John David Anglin wrote:
> Most I/O in the kernel is done using the kernel offset mapping. However, there
> is one API that uses aliased kernel address ranges:
>
>> The final category of APIs is for I/O to deliberately aliased address
>> ranges inside the kernel. Such aliases are set up by use of the
>> vmap/vmalloc API. Since kernel I/O goes via physical pages, the I/O
>> subsystem assumes that the user mapping and kernel offset mapping are
>> the only aliases. This isn't true for vmap aliases, so anything in
>> the kernel trying to do I/O to vmap areas must manually manage
>> coherency. It must do this by flushing the vmap range before doing
>> I/O and invalidating it after the I/O returns.
>
> For this reason, we should use the hardware lpa instruction to load the physical address
> of kernel virtual addresses in the driver code.
>
> I believe we only use the vmap/vmalloc API with old PA 1.x processors which don't have
> a sba, so we don't hit this problem.
>
> Tested on c3750, c8000 and rp3440.
>
> This patch includes the previous change to use implicit space register access in loading
> the coherence index as the two changes conflict.
Actually, I think it makes sense to push the drop-sr1/use-lci-without-sr1
change backward to the stable kernel series.
After that, in the second step, we could add the code to use lpa(), which
I don't think should go to stable series.
Would it be OK for you if we split it up into two patches?
Helge
>
> Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
> ---
> diff --git a/arch/parisc/include/asm/special_insns.h b/arch/parisc/include/asm/special_insns.h
> index 3d4dd68e181b..a303ae9a77f4 100644
> --- a/arch/parisc/include/asm/special_insns.h
> +++ b/arch/parisc/include/asm/special_insns.h
> @@ -2,6 +2,30 @@
> #ifndef __PARISC_SPECIAL_INSNS_H
> #define __PARISC_SPECIAL_INSNS_H
>
> +#define lpa(va) ({ \
> + unsigned long pa; \
> + __asm__ __volatile__( \
> + "copy %%r0,%0\n\t" \
> + "lpa %%r0(%1),%0" \
> + : "=r" (pa) \
> + : "r" (va) \
> + : "memory" \
> + ); \
> + pa; \
> +})
> +
> +#define lpa_user(va) ({ \
> + unsigned long pa; \
> + __asm__ __volatile__( \
> + "copy %%r0,%0\n\t" \
> + "lpa %%r0(%%sr3,%1),%0" \
> + : "=r" (pa) \
> + : "r" (va) \
> + : "memory" \
> + ); \
> + pa; \
> +})
> +
> #define mfctl(reg) ({ \
> unsigned long cr; \
> __asm__ __volatile__( \
> diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
> index 121f7603a595..217f15aafa4a 100644
> --- a/drivers/parisc/ccio-dma.c
> +++ b/drivers/parisc/ccio-dma.c
> @@ -562,14 +562,12 @@ ccio_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
> /* We currently only support kernel addresses */
> BUG_ON(sid != KERNEL_SPACE);
>
> - mtsp(sid,1);
> -
> /*
> ** WORD 1 - low order word
> ** "hints" parm includes the VALID bit!
> ** "dep" clobbers the physical address offset bits as well.
> */
> - pa = virt_to_phys(vba);
> + pa = lpa(vba);
> asm volatile("depw %1,31,12,%0" : "+r" (pa) : "r" (hints));
> ((u32 *)pdir_ptr)[1] = (u32) pa;
>
> @@ -594,7 +592,7 @@ ccio_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
> ** Grab virtual index [0:11]
> ** Deposit virt_idx bits into I/O PDIR word
> */
> - asm volatile ("lci %%r0(%%sr1, %1), %0" : "=r" (ci) : "r" (vba));
> + asm volatile ("lci %%r0(%1), %0" : "=r" (ci) : "r" (vba));
> asm volatile ("extru %1,19,12,%0" : "+r" (ci) : "r" (ci));
> asm volatile ("depw %1,15,12,%0" : "+r" (pa) : "r" (ci));
>
> diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
> index 8a9ea9bd050c..296668caf7e5 100644
> --- a/drivers/parisc/sba_iommu.c
> +++ b/drivers/parisc/sba_iommu.c
> @@ -569,11 +569,10 @@ sba_io_pdir_entry(u64 *pdir_ptr, space_t sid, unsigned long vba,
> u64 pa; /* physical address */
> register unsigned ci; /* coherent index */
>
> - pa = virt_to_phys(vba);
> + pa = lpa(vba);
> pa &= IOVP_MASK;
>
> - mtsp(sid,1);
> - asm("lci 0(%%sr1, %1), %0" : "=r" (ci) : "r" (vba));
> + asm("lci 0(%1), %0" : "=r" (ci) : "r" (vba));
> pa |= (ci >> PAGE_SHIFT) & 0xff; /* move CI (8 bits) into lowest byte */
>
> pa |= SBA_PDIR_VALID_BIT; /* set "valid" bit */
>
