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    Subject[PATCH v8 24/28] virt: gunyah: Add IO handlers
    Date
    Add framework for VM functions to handle stage-2 write faults from Gunyah
    guest virtual machines. IO handlers have a range of addresses which they
    apply to. Optionally, they may apply to only when the value written
    matches the IO handler's value.

    Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
    Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
    Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
    ---
    drivers/virt/gunyah/vm_mgr.c | 85 +++++++++++++++++++++++++++++++++++
    drivers/virt/gunyah/vm_mgr.h | 4 ++
    include/linux/gunyah_vm_mgr.h | 25 +++++++++++
    3 files changed, 114 insertions(+)

    diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
    index 3328b84fa681..dcca255bc11f 100644
    --- a/drivers/virt/gunyah/vm_mgr.c
    +++ b/drivers/virt/gunyah/vm_mgr.c
    @@ -165,6 +165,91 @@ void ghvm_remove_resource_ticket(struct gunyah_vm *ghvm, struct gunyah_vm_resour
    }
    EXPORT_SYMBOL_GPL(ghvm_remove_resource_ticket);

    +static inline bool gh_vm_io_handler_matches(struct gunyah_vm_io_handler *io_hdlr, u64 addr,
    + u64 len, u64 data)
    +{
    + u64 mask = BIT_ULL(io_hdlr->len * BITS_PER_BYTE) - 1;
    +
    + if (io_hdlr->addr != addr)
    + return false;
    +
    + if (!io_hdlr->datamatch)
    + return true;
    +
    + if (io_hdlr->len != len)
    + return false;
    +
    + return (data & mask) == (io_hdlr->data & mask);
    +}
    +
    +static struct gunyah_vm_io_handler *gh_vm_mgr_find_io_hdlr(struct gunyah_vm *ghvm, u64 addr,
    + u64 len, u64 data)
    +{
    + struct gunyah_vm_io_handler *io_hdlr = NULL;
    + struct rb_node *root = NULL;
    +
    + root = ghvm->mmio_handler_root.rb_node;
    + while (root) {
    + io_hdlr = rb_entry(root, struct gunyah_vm_io_handler, node);
    + if (addr < io_hdlr->addr)
    + root = root->rb_left;
    + else if (addr > io_hdlr->addr)
    + root = root->rb_right;
    + else if (gh_vm_io_handler_matches(io_hdlr, addr, len, data))
    + return io_hdlr;
    + }
    + return NULL;
    +}
    +
    +int gh_vm_mgr_mmio_write(struct gunyah_vm *ghvm, u64 addr, u32 len, u64 data)
    +{
    + struct gunyah_vm_io_handler *io_hdlr = NULL;
    +
    + io_hdlr = gh_vm_mgr_find_io_hdlr(ghvm, addr, len, data);
    + if (!io_hdlr)
    + return -ENODEV;
    +
    + if (io_hdlr->ops && io_hdlr->ops->write)
    + return io_hdlr->ops->write(io_hdlr, addr, len, data);
    +
    + return -ENODEV;
    +}
    +EXPORT_SYMBOL_GPL(gh_vm_mgr_mmio_write);
    +
    +int gh_vm_mgr_add_io_handler(struct gunyah_vm *ghvm, struct gunyah_vm_io_handler *io_hdlr)
    +{
    + struct rb_node **root, *parent = NULL;
    +
    + if (io_hdlr->datamatch &&
    + (!io_hdlr->len || io_hdlr->len > (sizeof(io_hdlr->data) * BITS_PER_BYTE)))
    + return -EINVAL;
    +
    + root = &ghvm->mmio_handler_root.rb_node;
    + while (*root) {
    + struct gunyah_vm_io_handler *curr = rb_entry(*root, struct gunyah_vm_io_handler,
    + node);
    +
    + parent = *root;
    + if (io_hdlr->addr < curr->addr)
    + root = &((*root)->rb_left);
    + else if (io_hdlr->addr > curr->addr)
    + root = &((*root)->rb_right);
    + else
    + return -EEXIST;
    + }
    +
    + rb_link_node(&io_hdlr->node, parent, root);
    + rb_insert_color(&io_hdlr->node, &ghvm->mmio_handler_root);
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(gh_vm_mgr_add_io_handler);
    +
    +void gh_vm_mgr_remove_io_handler(struct gunyah_vm *ghvm, struct gunyah_vm_io_handler *io_hdlr)
    +{
    + rb_erase(&io_hdlr->node, &ghvm->mmio_handler_root);
    +}
    +EXPORT_SYMBOL_GPL(gh_vm_mgr_remove_io_handler);
    +
    static void ghvm_put(struct kref *kref)
    {
    struct gunyah_vm *ghvm = container_of(kref, struct gunyah_vm, kref);
    diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
    index 8a71f97960bc..46ba2e530be2 100644
    --- a/drivers/virt/gunyah/vm_mgr.h
    +++ b/drivers/virt/gunyah/vm_mgr.h
    @@ -58,6 +58,8 @@ struct gunyah_vm {
    struct list_head resources;
    struct list_head resource_tickets;

    + struct rb_root mmio_handler_root;
    +
    struct list_head functions;
    };

    @@ -68,4 +70,6 @@ struct gunyah_vm_memory_mapping *gh_vm_mem_mapping_find(struct gunyah_vm *ghvm,
    struct gunyah_vm_memory_mapping *gh_vm_mem_mapping_find_mapping(struct gunyah_vm *ghvm,
    u64 gpa, u32 size);

    +int gh_vm_mgr_mmio_write(struct gunyah_vm *ghvm, u64 addr, u32 len, u64 data);
    +
    #endif
    diff --git a/include/linux/gunyah_vm_mgr.h b/include/linux/gunyah_vm_mgr.h
    index 3e6e6e0ab7f0..5b17cb54ba01 100644
    --- a/include/linux/gunyah_vm_mgr.h
    +++ b/include/linux/gunyah_vm_mgr.h
    @@ -79,4 +79,29 @@ struct gunyah_vm_resource_ticket {
    int ghvm_add_resource_ticket(struct gunyah_vm *ghvm, struct gunyah_vm_resource_ticket *ticket);
    void ghvm_remove_resource_ticket(struct gunyah_vm *ghvm, struct gunyah_vm_resource_ticket *ticket);

    +/*
    + * gunyah_vm_io_handler contains the info about an io device and its associated
    + * addr and the ops associated with the io device.
    + */
    +struct gunyah_vm_io_handler {
    + struct rb_node node;
    + u64 addr;
    +
    + bool datamatch;
    + u8 len;
    + u64 data;
    + struct gunyah_vm_io_handler_ops *ops;
    +};
    +
    +/*
    + * gunyah_vm_io_handler_ops contains function pointers associated with an iodevice.
    + */
    +struct gunyah_vm_io_handler_ops {
    + int (*read)(struct gunyah_vm_io_handler *io_dev, u64 addr, u32 len, u64 data);
    + int (*write)(struct gunyah_vm_io_handler *io_dev, u64 addr, u32 len, u64 data);
    +};
    +
    +int gh_vm_mgr_add_io_handler(struct gunyah_vm *ghvm, struct gunyah_vm_io_handler *io_dev);
    +void gh_vm_mgr_remove_io_handler(struct gunyah_vm *ghvm, struct gunyah_vm_io_handler *io_dev);
    +
    #endif
    --
    2.25.1
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