Hi Nicolin,
On 6/26/24 02:28, Nicolin Chen wrote:
> Nested SMMUv3 feature requires the support/presence of host-level SMMUv3
> instance(s). Add a helper to read the sysfs for the number of instances.
> Log them in a vms list using a new struct VirtNestedSmmu.
>
> This will be used by a following patch to assign a passthrough device to
> corresponding nested SMMUv3 instance.
Laterly the HostIOMMUDevice has been introduced to allow, among other
things, to pass information related to the physical IOMMU to the virtual
IOMMU.
I guess it would be well fitted to associate the viommu with its
underlying piommu.
I don't think we have such kind of host introspection in machine type.
Generally in can happen in the very device or in libvirt.
Thanks
Eric
>
> Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
> ---
> hw/arm/virt.c | 35 +++++++++++++++++++++++++++++++++++
> include/hw/arm/virt.h | 8 ++++++++
> 2 files changed, 43 insertions(+)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 71093d7c60..be3d8b0ce6 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -2668,6 +2668,37 @@ static char *virt_get_iommu(Object *obj, Error **errp)
> }
> }
>
> +static int virt_get_num_nested_smmus(VirtMachineState *vms, Error **errp)
> +{
> + VirtNestedSmmu *nested_smmu;
> + struct dirent *dent;
> + DIR *dir = NULL;
> + int num = 0;
> +
> + dir = opendir("/sys/class/iommu");
> + if (!dir) {
> + error_setg_errno(errp, errno, "couldn't open /sys/class/iommu");
> + return 0;
> + }
> +
> + while ((dent = readdir(dir))) {
> + if (!strncmp(dent->d_name, "smmu3.0x", 7)) {
> + nested_smmu = g_new0(VirtNestedSmmu, 1);
> + nested_smmu->index = num;
> + nested_smmu->smmu_node = g_strdup(dent->d_name);
> + QLIST_INSERT_HEAD(&vms->nested_smmu_list, nested_smmu, next);
> + num++;
> + }
> + }
> +
> + if (num == 0) {
> + error_setg_errno(errp, errno,
> + "couldn't find any SMMUv3 HW to setup nesting");
> + }
> +
> + return num;
> +}
> +
> static void virt_set_iommu(Object *obj, const char *value, Error **errp)
> {
> VirtMachineState *vms = VIRT_MACHINE(obj);
> @@ -2676,6 +2707,7 @@ static void virt_set_iommu(Object *obj, const char
> *value, Error **errp)
> vms->iommu = VIRT_IOMMU_SMMUV3;
> } else if (!strcmp(value, "nested-smmuv3")) {
> vms->iommu = VIRT_IOMMU_NESTED_SMMUV3;
> + vms->num_nested_smmus = virt_get_num_nested_smmus(vms, errp);
> } else if (!strcmp(value, "none")) {
> vms->iommu = VIRT_IOMMU_NONE;
> } else {
> @@ -3232,6 +3264,9 @@ static void virt_instance_init(Object *obj)
> /* The default root bus is attached to iommu by default */
> vms->default_bus_bypass_iommu = false;
>
> + /* Default disallows nested SMMU instantiation */
> + vms->num_nested_smmus = 0;
> +
> /* Default disallows RAS instantiation */
> vms->ras = false;
>
> diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
> index d5cbce1a30..e0c07527c4 100644
> --- a/include/hw/arm/virt.h
> +++ b/include/hw/arm/virt.h
> @@ -135,6 +135,12 @@ struct VirtMachineClass {
> bool no_ns_el2_virt_timer_irq;
> };
>
> +typedef struct VirtNestedSmmu {
> + int index;
> + char *smmu_node;
> + QLIST_ENTRY(VirtNestedSmmu) next;
> +} VirtNestedSmmu;
> +
> struct VirtMachineState {
> MachineState parent;
> Notifier machine_done;
> @@ -153,6 +159,7 @@ struct VirtMachineState {
> bool ras;
> bool mte;
> bool dtb_randomness;
> + int num_nested_smmus;
> OnOffAuto acpi;
> VirtGICType gic_version;
> IOMMUFDBackend *iommufd;
> @@ -178,6 +185,7 @@ struct VirtMachineState {
> char *oem_id;
> char *oem_table_id;
> bool ns_el2_virt_timer_irq;
> + QLIST_HEAD(, VirtNestedSmmu) nested_smmu_list;
> };
>
> #define VIRT_ECAM_ID(high) (high ? VIRT_HIGH_PCIE_ECAM : VIRT_PCIE_ECAM)
