Re: [PATCH 1/3] iommu/vt-d:Add support for detecting ACPI device in RMRR

Dan Carpenter
2020-08-26T11:03:27Z

On Wed, Aug 26, 2020 at 06:27:50AM -0400, FelixCuioc wrote:
> Some ACPI devices need to issue dma requests to access
> the reserved memory area.BIOS uses the device scope type
> ACPI_NAMESPACE_DEVICE in RMRR to report these ACPI devices.
> This patch add support for detecting ACPI devices in RMRR.
>
> Signed-off-by: FelixCuioc <FelixCui-oc@zhaoxin.com>
> ---
> drivers/iommu/intel/dmar.c | 74 ++++++++++++++++++++-----------------
> drivers/iommu/intel/iommu.c | 22 ++++++++++-
> include/linux/dmar.h | 12 +++++-
> 3 files changed, 72 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index 93e6345f3414..024ca38dba12 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -215,7 +215,7 @@ static bool dmar_match_pci_path(struct dmar_pci_notify_info *info, int bus,
> }
>
> /* Return: > 0 if match found, 0 if no match found, < 0 if error happens */
> -int dmar_insert_dev_scope(struct dmar_pci_notify_info *info,
> +int dmar_pci_insert_dev_scope(struct dmar_pci_notify_info *info,
> void *start, void*end, u16 segment,
> struct dmar_dev_scope *devices,
> int devices_cnt)
> @@ -304,7 +304,7 @@ static int dmar_pci_bus_add_dev(struct dmar_pci_notify_info *info)
>
> drhd = container_of(dmaru->hdr,
> struct acpi_dmar_hardware_unit, header);
> - ret = dmar_insert_dev_scope(info, (void *)(drhd + 1),
> + ret = dmar_pci_insert_dev_scope(info, (void *)(drhd + 1),
> ((void *)drhd) + drhd->header.length,
> dmaru->segment,
> dmaru->devices, dmaru->devices_cnt);
> @@ -696,48 +696,56 @@ dmar_find_matched_drhd_unit(struct pci_dev *dev)
>
> return dmaru;
> }
> -
> -static void __init dmar_acpi_insert_dev_scope(u8 device_number,
> - struct acpi_device *adev)
> +int dmar_acpi_insert_dev_scope(u8 device_number,

The patch deleted the blank line between functions. Make this function
bool, change the 1/0 to true/false. Add a comment explaining what the
return values mean.

> + struct acpi_device *adev,
> + void *start, void *end,
> + struct dmar_dev_scope *devices,
> + int devices_cnt)
> {
> - struct dmar_drhd_unit *dmaru;
> - struct acpi_dmar_hardware_unit *drhd;
> struct acpi_dmar_device_scope *scope;
> struct device *tmp;
> int i;
> struct acpi_dmar_pci_path *path;
>
> + for (; start < end; start += scope->length) {
> + scope = start;

Are we sure that there is enough space for sizeof(*scope) in end - start?
(I don't know this code so maybe we are).

> + if (scope->entry_type != ACPI_DMAR_SCOPE_TYPE_NAMESPACE)
> + continue;
> + if (scope->enumeration_id != device_number)
> + continue;
> + path = (void *)(scope + 1);
> + for_each_dev_scope(devices, devices_cnt, i, tmp)
> + if (tmp == NULL) {
> + devices[i].bus = scope->bus;
> + devices[i].devfn = PCI_DEVFN(path->device, path->function);
> + rcu_assign_pointer(devices[i].dev,
> + get_device(&adev->dev));
> + return 1;
> + }
> + WARN_ON(i >= devices_cnt);
> + }
> + return 0;
> +}
> +static int dmar_acpi_bus_add_dev(u8 device_number, struct acpi_device *adev)
> +{
> + struct dmar_drhd_unit *dmaru;
> + struct acpi_dmar_hardware_unit *drhd;
> + int ret = 0;

This initialization is never used.

> +
> for_each_drhd_unit(dmaru) {
> drhd = container_of(dmaru->hdr,
> struct acpi_dmar_hardware_unit,
> header);
> + ret = dmar_acpi_insert_dev_scope(device_number, adev, (void *)(drhd+1),
> + ((void *)drhd)+drhd->header.length,
> + dmaru->devices, dmaru->devices_cnt);
> + if (ret)
> + break;
> + }
> + ret = dmar_rmrr_add_acpi_dev(device_number, adev);

What about if dmar_acpi_insert_dev_scope() always returns zero, do we
still want to call dmar_rmrr_add_acpi_dev()?

>
> - for (scope = (void *)(drhd + 1);
> - (unsigned long)scope < ((unsigned long)drhd) + drhd->header.length;
> - scope = ((void *)scope) + scope->length) {
> - if (scope->entry_type != ACPI_DMAR_SCOPE_TYPE_NAMESPACE)
> - continue;
> - if (scope->enumeration_id != device_number)
> - continue;
> + return ret;
>
> - path = (void *)(scope + 1);
> - pr_info("ACPI device \"%s\" under DMAR at %llx as %02x:%02x.%d\n",
> - dev_name(&adev->dev), dmaru->reg_base_addr,
> - scope->bus, path->device, path->function);
> - for_each_dev_scope(dmaru->devices, dmaru->devices_cnt, i, tmp)
> - if (tmp == NULL) {
> - dmaru->devices[i].bus = scope->bus;
> - dmaru->devices[i].devfn = PCI_DEVFN(path->device,
> - path->function);
> - rcu_assign_pointer(dmaru->devices[i].dev,
> - get_device(&adev->dev));
> - return;
> - }
> - BUG_ON(i >= dmaru->devices_cnt);
> - }
> - }
> - pr_warn("No IOMMU scope found for ANDD enumeration ID %d (%s)\n",
> - device_number, dev_name(&adev->dev));
> }
>
> static int __init dmar_acpi_dev_scope_init(void)
> @@ -766,7 +774,7 @@ static int __init dmar_acpi_dev_scope_init(void)
> andd->device_name);
> continue;
> }
> - dmar_acpi_insert_dev_scope(andd->device_number, adev);
> + dmar_acpi_bus_add_dev(andd->device_number, adev);
> }
> }
> return 0;
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index ca557d351518..f774ef63d473 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4507,6 +4507,24 @@ int dmar_find_matched_atsr_unit(struct pci_dev *dev)
>
> return ret;
> }
> +int dmar_rmrr_add_acpi_dev(u8 device_number, struct acpi_device *adev)

Please add a blank line between functions.
> +{
> + int ret;
> + struct dmar_rmrr_unit *rmrru;
> + struct acpi_dmar_reserved_memory *rmrr;
> +
> + list_for_each_entry(rmrru, &dmar_rmrr_units, list) {
> + rmrr = container_of(rmrru->hdr,
> + struct acpi_dmar_reserved_memory,
> + header);
> + ret = dmar_acpi_insert_dev_scope(device_number, adev, (void *)(rmrr + 1),
> + ((void *)rmrr) + rmrr->header.length,
> + rmrru->devices, rmrru->devices_cnt);
> + if (ret)
> + break;
> + }
> + return 0;
> +}

regards,
dan carpenter