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SubjectRe: [PATCH v10 11/26] gunyah: rsc_mgr: Add RPC for sharing memory
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On 14/02/2023 21:24, Elliot Berman wrote:
>
> Gunyah resource manager provides API to manipulate stage 2 page tables.
> Manipulations are represented as a memory parcel. Memory parcels
> describe a list of memory regions (intermediate physical address and
> size), a list of new permissions for VMs, and the memory type (DDR or
> MMIO). Memory parcels are uniquely identified by a handle allocated by
> Gunyah. There are a few types of memory parcel sharing which Gunyah
> supports:
>
> - Sharing: the guest and host VM both have access
> - Lending: only the guest has access; host VM loses access
> - Donating: Permanently lent (not reclaimed even if guest shuts down)
>
> Memory parcels that have been shared or lent can be reclaimed by the
> host via an additional call. The reclaim operation restores the original
> access the host VM had to the memory parcel and removes the access to
> other VM.
>
> One point to note that memory parcels don't describe where in the guest
> VM the memory parcel should reside. The guest VM must accept the memory
> parcel either explicitly via a "gh_rm_mem_accept" call (not introduced
> here) or be configured to accept it automatically at boot. As the guest
> VM accepts the memory parcel, it also mentions the IPA it wants to place
> memory parcel.
>
> 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/rsc_mgr.h | 44 +++++++
> drivers/virt/gunyah/rsc_mgr_rpc.c | 185 ++++++++++++++++++++++++++++++
> include/linux/gunyah_rsc_mgr.h | 47 ++++++++
> 3 files changed, 276 insertions(+)
>
> diff --git a/drivers/virt/gunyah/rsc_mgr.h b/drivers/virt/gunyah/rsc_mgr.h
> index 7406237bc66d..9b23cefe02b0 100644
> --- a/drivers/virt/gunyah/rsc_mgr.h
> +++ b/drivers/virt/gunyah/rsc_mgr.h
> @@ -74,6 +74,12 @@ struct gh_rm;
> int gh_rm_call(struct gh_rm *rsc_mgr, u32 message_id, void *req_buff, size_t req_buff_size,
> void **resp_buf, size_t *resp_buff_size);
>
> +/* Message IDs: Memory Management */
> +#define GH_RM_RPC_MEM_LEND 0x51000012
> +#define GH_RM_RPC_MEM_SHARE 0x51000013
> +#define GH_RM_RPC_MEM_RECLAIM 0x51000015
> +#define GH_RM_RPC_MEM_APPEND 0x51000018
> +
> /* Message IDs: VM Management */
> #define GH_RM_RPC_VM_ALLOC_VMID 0x56000001
> #define GH_RM_RPC_VM_DEALLOC_VMID 0x56000002
> @@ -90,6 +96,44 @@ struct gh_rm_vm_common_vmid_req {
> __le16 reserved0;
> } __packed;
>
> +/* Call: MEM_LEND, MEM_SHARE */
> +struct gh_rm_mem_share_req_header {
> + u8 mem_type;
> + u8 reserved0;
> +#define GH_MEM_SHARE_REQ_FLAGS_APPEND BIT(1)
> + u8 flags;
> + u8 reserved1;
> + __le32 label;
> +} __packed;
> +
> +struct gh_rm_mem_share_req_acl_section {
> + __le32 n_entries;
> + struct gh_rm_mem_acl_entry entries[];
> +};
> +
> +struct gh_rm_mem_share_req_mem_section {
> + __le16 n_entries;
> + __le16 reserved0;
> + struct gh_rm_mem_entry entries[];
> +};
> +
> +/* Call: MEM_RELEASE */
> +struct gh_rm_mem_release_req {
> + __le32 mem_handle;
> + u8 flags; /* currently not used */
> + __le16 reserved0;
> + u8 reserved1;
> +} __packed;
> +
> +/* Call: MEM_APPEND */
> +struct gh_rm_mem_append_req_header {
> + __le32 mem_handle;
> +#define GH_MEM_APPEND_REQ_FLAGS_END BIT(0)
> + u8 flags;
> + __le16 reserved0;
> + u8 reserved1;
> +} __packed;
> +
> /* Call: VM_ALLOC */
> struct gh_rm_vm_alloc_vmid_resp {
> __le16 vmid;
> diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
> index 4515cdd80106..0c83b097fec9 100644
> --- a/drivers/virt/gunyah/rsc_mgr_rpc.c
> +++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
> @@ -7,6 +7,8 @@
>
> #include "rsc_mgr.h"
>
> +#define GH_RM_MAX_MEM_ENTRIES 512
> +
> /*
> * Several RM calls take only a VMID as a parameter and give only standard
> * response back. Deduplicate boilerplate code by using this common call.
> @@ -22,6 +24,189 @@ static int gh_rm_common_vmid_call(struct gh_rm *rm, u32 message_id, u16 vmid)
> return gh_rm_call(rm, message_id, &req_payload, sizeof(req_payload), &resp, &resp_size);
> }
>
> +static int _gh_rm_mem_append(struct gh_rm *rm, u32 mem_handle, bool end_append,
> + struct gh_rm_mem_entry *mem_entries, size_t n_mem_entries)
> +{
> + struct gh_rm_mem_share_req_mem_section *mem_section;
> + struct gh_rm_mem_append_req_header *req_header;
> + size_t msg_size = 0, resp_size;
> + void *msg, *resp;
> + int ret;
> +
> + msg_size += sizeof(struct gh_rm_mem_append_req_header);
> + msg_size += struct_size(mem_section, entries, n_mem_entries);
> +
> + msg = kzalloc(msg_size, GFP_KERNEL);
> + if (!msg)
> + return -ENOMEM;
> +
> + req_header = msg;
> + mem_section = (void *)req_header + sizeof(struct gh_rm_mem_append_req_header);
> +
> + req_header->mem_handle = cpu_to_le32(mem_handle);
> + if (end_append)
> + req_header->flags |= GH_MEM_APPEND_REQ_FLAGS_END;
> +
> + mem_section->n_entries = cpu_to_le16(n_mem_entries);
> + memcpy(mem_section->entries, mem_entries, sizeof(*mem_entries) * n_mem_entries);
> +
> + ret = gh_rm_call(rm, GH_RM_RPC_MEM_APPEND, msg, msg_size, &resp, &resp_size);

I have seen this pattern, where we pass &resp eventhough we are not
expecting a response.

Can we make this explicit by passing NULL. This can also help to find
any leaks of resp in case they are not freed by the caller.

ret = gh_rm_call(rm, GH_RM_RPC_MEM_APPEND, msg, msg_size, NULL, NULL);

> + kfree(msg);
> +
> + return ret;
> +}
> +
> +static int gh_rm_mem_append(struct gh_rm *rm, u32 mem_handle,
> + struct gh_rm_mem_entry *mem_entries, size_t n_mem_entries)
> +{
> + bool end_append;
> + int ret = 0;
> + size_t n;
> +
> + while (n_mem_entries) {
> + if (n_mem_entries > GH_RM_MAX_MEM_ENTRIES) {
> + end_append = false;
> + n = GH_RM_MAX_MEM_ENTRIES;
> + } else {
> + end_append = true;
> + n = n_mem_entries;
> + }
> +
> + ret = _gh_rm_mem_append(rm, mem_handle, end_append, mem_entries, n);
> + if (ret)
> + break;
> +
> + mem_entries += n;
> + n_mem_entries -= n;
> + }
> +
> + return ret;
> +}
> +
> +static int gh_rm_mem_lend_common(struct gh_rm *rm, u32 message_id, struct gh_rm_mem_parcel *p)
> +{
> + size_t msg_size = 0, initial_mem_entries = p->n_mem_entries, resp_size;
> + struct gh_rm_mem_share_req_acl_section *acl_section;
> + struct gh_rm_mem_share_req_mem_section *mem_section;
> + struct gh_rm_mem_share_req_header *req_header;
> + u32 *attr_section;
> + __le32 *resp;
> + void *msg;
> + int ret;
> +
> + if (!p->acl_entries || !p->n_acl_entries || !p->mem_entries || !p->n_mem_entries ||
> + p->n_acl_entries > U8_MAX || p->mem_handle != GH_MEM_HANDLE_INVAL)
> + return -EINVAL;
> +
> + if (initial_mem_entries > GH_RM_MAX_MEM_ENTRIES)
> + initial_mem_entries = GH_RM_MAX_MEM_ENTRIES;
> +
> + /* The format of the message goes:
> + * request header
> + * ACL entries (which VMs get what kind of access to this memory parcel)
> + * Memory entries (list of memory regions to share)
> + * Memory attributes (currently unused, we'll hard-code the size to 0)
> + */
> + msg_size += sizeof(struct gh_rm_mem_share_req_header);
> + msg_size += struct_size(acl_section, entries, p->n_acl_entries);
> + msg_size += struct_size(mem_section, entries, initial_mem_entries);
> + msg_size += sizeof(u32); /* for memory attributes, currently unused */
> +
> + msg = kzalloc(msg_size, GFP_KERNEL);
> + if (!msg)
> + return -ENOMEM;
> +
> + req_header = msg;
> + acl_section = (void *)req_header + sizeof(*req_header);
> + mem_section = (void *)acl_section + struct_size(acl_section, entries, p->n_acl_entries);
> + attr_section = (void *)mem_section + struct_size(mem_section, entries, initial_mem_entries);
> +
> + req_header->mem_type = p->mem_type;
> + if (initial_mem_entries != p->n_mem_entries)
> + req_header->flags |= GH_MEM_SHARE_REQ_FLAGS_APPEND;
> + req_header->label = cpu_to_le32(p->label);
> +
> + acl_section->n_entries = cpu_to_le32(p->n_acl_entries);
> + memcpy(acl_section->entries, p->acl_entries, sizeof(*(p->acl_entries)) * p->n_acl_entries);
> +
> + mem_section->n_entries = cpu_to_le16(initial_mem_entries);
> + memcpy(mem_section->entries, p->mem_entries,
> + sizeof(*(p->mem_entries)) * initial_mem_entries);
> +
> + /* Set n_entries for memory attribute section to 0 */
> + *attr_section = 0;
> +
> + ret = gh_rm_call(rm, message_id, msg, msg_size, (void **)&resp, &resp_size);
> + kfree(msg);
> +
> + if (ret)
> + return ret;
> +
> + p->mem_handle = le32_to_cpu(*resp);
> +
> + if (initial_mem_entries != p->n_mem_entries) {
> + ret = gh_rm_mem_append(rm, p->mem_handle,
> + &p->mem_entries[initial_mem_entries],
> + p->n_mem_entries - initial_mem_entries);
> + if (ret) {
> + gh_rm_mem_reclaim(rm, p);
> + p->mem_handle = GH_MEM_HANDLE_INVAL;
> + }
> + }
> +
> + kfree(resp);
> + return ret;
> +}
> +
> +/**
> + * gh_rm_mem_lend() - Lend memory to other virtual machines.
> + * @rm: Handle to a Gunyah resource manager
> + * @parcel: Package the memory information of the memory to be lent.
> + *
> + * Lending removes Linux's access to the memory while the memory parcel is lent.
> + */
> +int gh_rm_mem_lend(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel)
> +{
> + return gh_rm_mem_lend_common(rm, GH_RM_RPC_MEM_LEND, parcel);
> +}
> +
> +
> +/**
> + * gh_rm_mem_share() - Share memory with other virtual machines.
> + * @rm: Handle to a Gunyah resource manager
> + * @parcel: Package the memory information of the memory to be shared.
> + *
> + * Sharing keeps Linux's access to the memory while the memory parcel is shared.
> + */
> +int gh_rm_mem_share(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel)
> +{
> + return gh_rm_mem_lend_common(rm, GH_RM_RPC_MEM_SHARE, parcel);
> +}
> +
> +/**
> + * gh_rm_mem_reclaim() - Reclaim a memory parcel
> + * @rm: Handle to a Gunyah resource manager
> + * @parcel: Package the memory information of the memory to be reclaimed.
> + *
> + * RM maps the associated memory back into the stage-2 page tables of the owner VM.
> + */
> +int gh_rm_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel)
> +{
> + struct gh_rm_mem_release_req req = {
> + .mem_handle = cpu_to_le32(parcel->mem_handle),
> + };
> + size_t resp_size;
> + void *resp;
> + int ret;
> +
> + ret = gh_rm_call(rm, GH_RM_RPC_MEM_RECLAIM, &req, sizeof(req), &resp, &resp_size);
> + /* Do not call platform mem reclaim hooks: the reclaim didn't happen*/
> + if (ret)
> + return ret;
> +
how about

return gh_rm_call(rm, GH_RM_RPC_MEM_RECLAIM, &req, sizeof(req), &resp,
&resp_size);


> + return ret;
> +}
> +
> /**
> * gh_rm_alloc_vmid() - Allocate a new VM in Gunyah. Returns the VM identifier.
> * @rm: Handle to a Gunyah resource manager
> diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
> index e7bd29f8be6e..2d8b8b6cc394 100644
> --- a/include/linux/gunyah_rsc_mgr.h
> +++ b/include/linux/gunyah_rsc_mgr.h
> @@ -11,6 +11,7 @@
> #include <linux/gunyah.h>
>
> #define GH_VMID_INVAL U16_MAX
> +#define GH_MEM_HANDLE_INVAL U32_MAX
>
> /* Gunyah recognizes VMID0 as an alias to the current VM's ID */
> #define GH_VMID_SELF 0
> @@ -54,7 +55,53 @@ struct gh_rm_vm_status_payload {
>
> #define GH_RM_NOTIFICATION_VM_STATUS 0x56100008
>
> +struct gh_rm_mem_acl_entry {
> + __le16 vmid;
> +#define GH_RM_ACL_X BIT(0)
> +#define GH_RM_ACL_W BIT(1)
> +#define GH_RM_ACL_R BIT(2)
> + u8 perms;
> + u8 reserved;
> +} __packed;
> +
> +struct gh_rm_mem_entry {
> + __le64 ipa_base;
> + __le64 size;
> +} __packed;
> +
> +enum gh_rm_mem_type {
> + GH_RM_MEM_TYPE_NORMAL = 0,
> + GH_RM_MEM_TYPE_IO = 1,
> +};
> +
> +/*
> + * struct gh_rm_mem_parcel - Package info about memory to be lent/shared/donated/reclaimed
> + * @mem_type: The type of memory: normal (DDR) or IO
> + * @label: An client-specified identifier which can be used by the other VMs to identify the purpose
> + * of the memory parcel.
> + * @acl_entries: An array of access control entries. Each entry specifies a VM and what access
> + * is allowed for the memory parcel.
> + * @n_acl_entries: Count of the number of entries in the `acl_entries` array.
> + * @mem_entries: An list of regions to be associated with the memory parcel. Addresses should be
> + * (intermediate) physical addresses from Linux's perspective.
> + * @n_mem_entries: Count of the number of entries in the `mem_entries` array.
> + * @mem_handle: On success, filled with memory handle that RM allocates for this memory parcel
> + */
> +struct gh_rm_mem_parcel {
> + enum gh_rm_mem_type mem_type;
> + u32 label;
> + size_t n_acl_entries;
> + struct gh_rm_mem_acl_entry *acl_entries;
> + size_t n_mem_entries;
> + struct gh_rm_mem_entry *mem_entries;
> + u32 mem_handle;
> +};
> +
> /* RPC Calls */
> +int gh_rm_mem_lend(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel);
> +int gh_rm_mem_share(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel);
> +int gh_rm_mem_reclaim(struct gh_rm *rm, struct gh_rm_mem_parcel *parcel);
> +
> int gh_rm_alloc_vmid(struct gh_rm *rm, u16 vmid);
> int gh_rm_dealloc_vmid(struct gh_rm *rm, u16 vmid);
> int gh_rm_vm_reset(struct gh_rm *rm, u16 vmid);

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