On 2025-08-12 15:57:13 Tue, Haren Myneni wrote:
> The hypervisor assigns one pipe per partition for all sources and
> assigns new pipe after migration. Also the partition ID that is
> used by source as its target ID may be changed after the migration.
> So disable hvpipe during SUSPEND event with ‘hvpipe enable’ system
> parameter value = 0 and enable it after migration during RESUME
> event with hvpipe enable’ system parameter value = 1.
>
> The user space calls such as ioctl()/ read() / write() / poll()
> returns -ENXIO between SUSPEND and RESUME events. The user space
> process can close FD and reestablish connection with new FD after
> migration if needed (Example: source IDs are changed).
>
> Signed-off-by: Haren Myneni <ha...@linux.ibm.com>
> ---
> arch/powerpc/platforms/pseries/mobility.c | 3 +
> arch/powerpc/platforms/pseries/papr-hvpipe.c | 64 ++++++++++++++++++++
> arch/powerpc/platforms/pseries/papr-hvpipe.h | 6 ++
> 3 files changed, 73 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/mobility.c
> b/arch/powerpc/platforms/pseries/mobility.c
> index 62bd8e2d5d4c..95fe802ccdfd 100644
> --- a/arch/powerpc/platforms/pseries/mobility.c
> +++ b/arch/powerpc/platforms/pseries/mobility.c
> @@ -28,6 +28,7 @@
> #include <asm/rtas.h>
> #include "pseries.h"
> #include "vas.h" /* vas_migration_handler() */
> +#include "papr-hvpipe.h" /* hvpipe_migration_handler() */
> #include "../../kernel/cacheinfo.h"
>
> static struct kobject *mobility_kobj;
> @@ -744,6 +745,7 @@ static int pseries_migrate_partition(u64 handle)
> * by closing VAS windows at the beginning of this function.
> */
> vas_migration_handler(VAS_SUSPEND);
> + hvpipe_migration_handler(HVPIPE_SUSPEND);
>
> ret = wait_for_vasi_session_suspending(handle);
> if (ret)
> @@ -770,6 +772,7 @@ static int pseries_migrate_partition(u64 handle)
>
> out:
> vas_migration_handler(VAS_RESUME);
> + hvpipe_migration_handler(HVPIPE_RESUME);
>
> return ret;
> }
> diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c
> b/arch/powerpc/platforms/pseries/papr-hvpipe.c
> index bc3d1f0b4491..0edc1a29d64d 100644
> --- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
> +++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
> @@ -27,6 +27,7 @@ static unsigned char hvpipe_ras_buf[RTAS_ERROR_LOG_MAX];
> static struct workqueue_struct *papr_hvpipe_wq;
> static struct work_struct *papr_hvpipe_work = NULL;
> static int hvpipe_check_exception_token;
> +static bool hvpipe_feature;
>
> /*
> * New PowerPC FW provides support for partitions and various
> @@ -233,6 +234,12 @@ static ssize_t papr_hvpipe_handle_write(struct file
> *file,
> unsigned long ret, len;
> char *area_buf;
>
> + /*
> + * Return -ENXIO during migration
> + */
> + if (!hvpipe_feature)
> + return -ENXIO;
> +
> if (!src_info)
> return -EIO;
>
> @@ -325,6 +332,12 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,
> struct papr_hvpipe_hdr hdr;
> long ret;
>
> + /*
> + * Return -ENXIO during migration
> + */
> + if (!hvpipe_feature)
> + return -ENXIO;
> +
> if (!src_info)
> return -EIO;
>
> @@ -401,6 +414,12 @@ static unsigned int papr_hvpipe_handle_poll(struct file
> *filp,
> {
> struct hvpipe_source_info *src_info = filp->private_data;
>
> + /*
> + * Return -ENXIO during migration
> + */
> + if (!hvpipe_feature)
> + return -ENXIO;
> +
> if (!src_info)
> return -EIO;
>
> @@ -530,6 +549,12 @@ static long papr_hvpipe_dev_ioctl(struct file *filp,
> unsigned int ioctl,
> u32 srcID;
> long ret;
>
> + /*
> + * Return -ENXIO during migration
> + */
> + if (!hvpipe_feature)
> + return -ENXIO;
> +
> if (get_user(srcID, argp))
> return -EFAULT;
>
> @@ -688,6 +713,44 @@ static int __init enable_hvpipe_IRQ(void)
> return 0;
> }
>
> +void hvpipe_migration_handler(int action)
> +{
> + pr_info("hvpipe migration event %d\n", action);
> +
> + /*
> + * HVPIPE is not used (Failed to create /dev/papr-hvpipe).
> + * So nothing to do for migration.
> + */
> + if (!papr_hvpipe_work)
> + return;
> +
> + switch (action) {
> + case HVPIPE_SUSPEND:
> + if (hvpipe_feature) {
> + /*
> + * Disable hvpipe_feature to the user space.
> + * It will be enabled with RESUME event.
> + */
> + hvpipe_feature = false;
> + /*
> + * set system parameter hvpipe 'disable'
> + */
> + set_hvpipe_sys_param(0);
> + }
> + break;
> + case HVPIPE_RESUME:
> + /*
> + * set system parameter hvpipe 'enable'
> + */
> + if (!set_hvpipe_sys_param(1))
> + hvpipe_feature = true;
> + else
> + pr_err("hvpipe is not enabled after migration\n");
So we will end up in else condtion if destination partition does not
have hvpipe capability ?
Thanks,
-Mahesh.
> +
> + break;
> + }
> +}
> +
> static const struct file_operations papr_hvpipe_ops = {
> .unlocked_ioctl = papr_hvpipe_dev_ioctl,
> };
> @@ -731,6 +794,7 @@ static int __init papr_hvpipe_init(void)
>
> if (!ret) {
> pr_info("hvpipe feature is enabled\n");
> + hvpipe_feature = true;
> return 0;
> } else
> pr_err("hvpipe feature is not enabled %d\n", ret);
> diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h
> b/arch/powerpc/platforms/pseries/papr-hvpipe.h
> index aab7f77e087d..c343f4230865 100644
> --- a/arch/powerpc/platforms/pseries/papr-hvpipe.h
> +++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
> @@ -11,6 +11,11 @@
>
> #define HVPIPE_HDR_LEN sizeof(struct papr_hvpipe_hdr)
>
> +enum hvpipe_migrate_action {
> + HVPIPE_SUSPEND,
> + HVPIPE_RESUME,
> +};
> +
> struct hvpipe_source_info {
> struct list_head list; /* list of sources */
> u32 srcID;
> @@ -33,4 +38,5 @@ struct hvpipe_event_buf {
> /* with specified src ID */
> };
>
> +void hvpipe_migration_handler(int action);
> #endif /* _PAPR_HVPIPE_H */
> --
> 2.43.5
>
>
--
Mahesh J Salgaonkar
