2021-09-09 04:09:55

by Wang Lu

Subject: [PATCH] PCI/P2PDMA: fix the wrong dma address calculation when map sg

The bus offset is bus address - physical address,
so the calculation in __pci_p2pdma_map_sg should be:
bus address = physical address + bus offset.

Signed-off-by: Wang Lu <[email protected]>
---
drivers/pci/p2pdma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 50cdde3e9a8b..327882638b30 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -874,7 +874,7 @@ static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap,
int i;

for_each_sg(sg, s, nents, i) {
- s->dma_address = sg_phys(s) - p2p_pgmap->bus_offset;
+ s->dma_address = sg_phys(s) + p2p_pgmap->bus_offset;
sg_dma_len(s) = s->length;
}

--
2.17.1

2021-09-09 16:53:52

by Logan Gunthorpe

Subject: Re: [PATCH] PCI/P2PDMA: fix the wrong dma address calculation when map sg

On 2021-09-08 9:25 p.m., Wang Lu wrote:
> The bus offset is bus address - physical address,
> so the calculation in __pci_p2pdma_map_sg should be:
> bus address = physical address + bus offset.
>
> Signed-off-by: Wang Lu <[email protected]>

Thanks, yes I believe my math was wrong here.

It was never tested on any machine that has a non-zero bus-offset.

Reviewed-by: Logan Gunthorpe <[email protected]>

2021-09-09 17:32:15

by Bjorn Helgaas

Subject: Re: [PATCH] PCI/P2PDMA: fix the wrong dma address calculation when map sg

On Thu, Sep 09, 2021 at 11:25:28AM +0800, Wang Lu wrote:
> The bus offset is bus address - physical address,
> so the calculation in __pci_p2pdma_map_sg should be:
> bus address = physical address + bus offset.
>
> Signed-off-by: Wang Lu <[email protected]>

Applied with Logan's reviewed-by to pci/p2pdma for v5.16, thanks!

I fixed the subject line and commit log for you to follow the usual
conventions.

> ---
> drivers/pci/p2pdma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 50cdde3e9a8b..327882638b30 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -874,7 +874,7 @@ static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap,
> int i;
>
> for_each_sg(sg, s, nents, i) {
> - s->dma_address = sg_phys(s) - p2p_pgmap->bus_offset;
> + s->dma_address = sg_phys(s) + p2p_pgmap->bus_offset;
> sg_dma_len(s) = s->length;
> }
>
> --
> 2.17.1
>
>
>