[PATCH v0 04/15] mshv: Provide a way to get partition id if running in a VMM process

[Mukesh R <mrathor@linux.microsoft.com>]

From: Mukesh Rathor <mrathor@linux.microsoft.com>

Many PCI passthru related hypercalls require partition id of the target
guest. Guests are actually managed by MSHV driver and the partition id
is only maintained there. Add a field in the partition struct in MSHV
driver to save the tgid of the VMM process creating the partition,
and add a function there to retrieve partition id if valid VMM tgid.

Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
---
 drivers/hv/mshv_root.h         |  1 +
 drivers/hv/mshv_root_main.c    | 35 +++++++++++++++++++++++++++-------
 include/asm-generic/mshyperv.h |  1 +
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/hv/mshv_root.h b/drivers/hv/mshv_root.h
index 3c1d88b36741..c3753b009fd8 100644
--- a/drivers/hv/mshv_root.h
+++ b/drivers/hv/mshv_root.h
@@ -134,6 +134,7 @@ struct mshv_partition {
 
 	struct mshv_girq_routing_table __rcu *pt_girq_tbl;
 	u64 isolation_type;
+	pid_t pt_vmm_tgid;
 	bool import_completed;
 	bool pt_initialized;
 };
diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c
index 1134a82c7881..83c7bad269a0 100644
--- a/drivers/hv/mshv_root_main.c
+++ b/drivers/hv/mshv_root_main.c
@@ -1823,6 +1823,20 @@ mshv_partition_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+/* Given a process tgid, return partition id if it is a VMM process */
+u64 mshv_pid_to_partid(pid_t tgid)
+{
+	struct mshv_partition *pt;
+	int i;
+
+	hash_for_each_rcu(mshv_root.pt_htable, i, pt, pt_hnode)
+		if (pt->pt_vmm_tgid == tgid)
+			return pt->pt_id;
+
+	return HV_PARTITION_ID_INVALID;
+}
+EXPORT_SYMBOL_GPL(mshv_pid_to_partid);
+
 static int
 add_partition(struct mshv_partition *partition)
 {
@@ -1987,13 +2001,20 @@ mshv_ioctl_create_partition(void __user *user_arg, struct device *module_dev)
 		goto delete_partition;
 
 	ret = mshv_init_async_handler(partition);
-	if (!ret) {
-		ret = FD_ADD(O_CLOEXEC, anon_inode_getfile("mshv_partition",
-							   &mshv_partition_fops,
-							   partition, O_RDWR));
-		if (ret >= 0)
-			return ret;
-	}
+	if (ret)
+		goto rem_partition;
+
+	ret = FD_ADD(O_CLOEXEC, anon_inode_getfile("mshv_partition",
+						   &mshv_partition_fops,
+						   partition, O_RDWR));
+	if (ret < 0)
+		goto rem_partition;
+
+	partition->pt_vmm_tgid = current->tgid;
+
+	return ret;
+
+rem_partition:
 	remove_partition(partition);
 delete_partition:
 	hv_call_delete_partition(partition->pt_id);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index ecedab554c80..e46a38916e76 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -211,6 +211,7 @@ void __init ms_hyperv_late_init(void);
 int hv_common_cpu_init(unsigned int cpu);
 int hv_common_cpu_die(unsigned int cpu);
 void hv_identify_partition_type(void);
+u64 mshv_pid_to_partid(pid_t tgid);
 
 /**
  * hv_cpu_number_to_vp_number() - Map CPU to VP.
-- 
2.51.2.vfs.0.1