[dpdk-dev] [PATCH v2 3/5] bus/pci: use IOVAs check when setting IOVA mode
Burakov, Anatoly
anatoly.burakov at intel.com
Wed Oct 3 14:55:55 CEST 2018
On 31-Aug-18 1:50 PM, Alejandro Lucero wrote:
> Although VT-d emulation currently only supports 39 bits, it could
> be iovas being within that supported range. This patch allows
> IOVA mode in such a case.
>
> Indeed, memory initialization code can be modified for using lower
> virtual addresses than those used by the kernel for 64 bits processes
> by default, and therefore memsegs iovas can use 39 bits or less for
> most system. And this is likely 100% true for VMs.
>
> Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com>
> ---
> drivers/bus/pci/linux/pci.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/bus/pci/linux/pci.c b/drivers/bus/pci/linux/pci.c
> index 04648ac..215dc10 100644
> --- a/drivers/bus/pci/linux/pci.c
> +++ b/drivers/bus/pci/linux/pci.c
> @@ -588,10 +588,11 @@
> fclose(fp);
>
> mgaw = ((vtd_cap_reg & VTD_CAP_MGAW_MASK) >> VTD_CAP_MGAW_SHIFT) + 1;
> - if (mgaw < X86_VA_WIDTH)
> - return false;
>
> - return true;
> + if (!rte_eal_check_dma_mask(mgaw))
> + return true;
> + else
> + return false;
return rte_eal_check_dma_mask(mgaw) == 0; ?
> }
> #elif defined(RTE_ARCH_PPC_64)
> static bool
> @@ -615,13 +616,17 @@
> {
> struct rte_pci_device *dev = NULL;
> struct rte_pci_driver *drv = NULL;
> + int iommu_dma_mask_check_done = 0;
>
> FOREACH_DRIVER_ON_PCIBUS(drv) {
> FOREACH_DEVICE_ON_PCIBUS(dev) {
> if (!rte_pci_match(drv, dev))
> continue;
> - if (!pci_one_device_iommu_support_va(dev))
> - return false;
> + if (!iommu_dma_mask_check_done) {
> + if (!pci_one_device_iommu_support_va(dev))
> + return false;
> + iommu_dma_mask_check_done = 1;
> + }
> }
The commit message doesn't explain why are we only checking a single
device. Indeed, i am not 100% clear as to why, so some explanation in
the commit message and preferably a comment in code would be more than
welcome :)
> }
> return true;
>
--
Thanks,
Anatoly
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