On Thu, 19 Jan 2023 01:11:44 +0000, Gavin Shan <gshan@xxxxxxxxxx> wrote: > > I will have vgic_write_guest_lock() in v2. Note that those 3 paths can't be > running in parallel since one switch is shared by them. Alternatively, we > extend struct vgic_dist::save_tables_in_progress from 'bool' to 'unsigned long'. > Several bit is defined for each site as below. In this way, the 3 paths can be > running in parallel: > > unsigned long struct vgic_dist::save_tables_in_progress > > #define VGIC_DIST_SAVE_ITS_ITE 0 /* ITS Translation Entry */ > #define VGIC_DIST_SAVE_ITS_DTE 1 /* ITS Device Table Entry */ > #define VGIC_DIST_SAVE_ITS_CTE 2 /* ITS Collection Table Entry */ > #define VGIC_DIST_SAVE_ITS_CT 3 /* ITS Collection Table */ > #define VGIC_DIST_SAVE_VGIC3_LPI 4 /* VGIC3 LPI Pending Status */ > #define VGIC_DIST_SAVE_VGIC3_PENDING_TABLE 5 /* VGIC3 Pending Table */ > > The drawback is the calls are limited to 64. If those 3 paths can't be running > in parallel, we needn't the extension at all. It should all be completely sequential. KVM_DEV_ARM_ITS_SAVE_TABLES runs in a context where everything is locked, and so is VGIC_DIST_SAVE_VGIC3_PENDING_TABLE. M. -- Without deviation from the norm, progress is not possible.
