On Mon, 2025-08-25 at 11:28 +0530, Mahesh J Salgaonkar wrote: > On 2025-08-12 15:57:08 Tue, Haren Myneni wrote: > > ibm,send-hvpipe-msg RTAS call is used to send data to the source > > (Ex: Hardware Management Console) over the hypervisor pipe. The > > maximum data length of 4048 bytes is supported with this RTAS call > > right now. The user space uses write() to send this payload which > > invokes this RTAS. Then the write returns the buffer length > > (including papr_hvpipe_hdr length) to the user space for success > > or RTAS failure error. > > > > ibm,send-hvpipe-msg call takes source ID as target and the buffer > > in the form of buffer list. The buffer list format consists of > > work area of size 4K to hold buffer list and number of 4K work > > areas depends on buffers is as follows: > > > > Length of Buffer List in bytes > > Address of 4K buffer 1 > > Length of 4K buffer 1 used > > ... > > Address of 4K buffer n > > Length of 4K buffer n used > > > > Only one buffer is used right now because of max payload size is > > 4088 bytes. writev() can be used in future when supported more > > Do you mean 4048 ? Yes typo error. It should be 4048 bytes as mentioned in the code.
> > > than one buffer. > > > > Signed-off-by: Haren Myneni <[email protected]> > > --- > > arch/powerpc/platforms/pseries/papr-hvpipe.c | 120 > > ++++++++++++++++++- > > arch/powerpc/platforms/pseries/papr-hvpipe.h | 7 ++ > > 2 files changed, 126 insertions(+), 1 deletion(-) > > > > diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c > > b/arch/powerpc/platforms/pseries/papr-hvpipe.c > > index 5768d072859d..c30f4d75e645 100644 > > --- a/arch/powerpc/platforms/pseries/papr-hvpipe.c > > +++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c > > @@ -14,6 +14,7 @@ > > #include <linux/of.h> > > #include <asm/machdep.h> > > #include <asm/rtas.h> > > +#include <asm/rtas-work-area.h> > > #include <uapi/asm/papr-hvpipe.h> > > #include "pseries.h" > > #include "papr-hvpipe.h" > > @@ -59,6 +60,51 @@ static LIST_HEAD(hvpipe_src_list); > > * return code for failure. > > */ > > > > +/* > > + * ibm,send-hvpipe-msg RTAS call > > + * @area: Caller-provided work area buffer to send. > > + * @srcID: Target source for the send pipe message. > > + */ > > +static int rtas_ibm_send_hvpipe_msg(struct rtas_work_area *area, > > u32 srcID) > > +{ > > + const s32 token = > > rtas_function_token(RTAS_FN_IBM_SEND_HVPIPE_MSG); > > + s32 fwrc; > > + int ret; > > + > > + if (token == RTAS_UNKNOWN_SERVICE) > > + return -ENOENT; > > + > > + do { > > + fwrc = rtas_call(token, 2, 1, NULL, srcID, > > + rtas_work_area_phys(area)); > > + > > + } while (rtas_busy_delay(fwrc)); > > + > > + switch (fwrc) { > > + case RTAS_SUCCESS: > > + ret = 0; > > + break; > > + case RTAS_HARDWARE_ERROR: > > + ret = -EIO; > > + break; > > + case RTAS_INVALID_PARAMETER: > > + ret = -EINVAL; > > + break; > > + case RTAS_HVPIPE_CLOSED: > > + ret = -EACCES; > > The status -4 is Pipe connection is closed/unavailabe. Instead of > permission denied does it make sense to return -EPIPE (Broken pipe) ? Agree, The user space should close all FDs when sees this error. Will change it to -EPIPE. Thanks for your suggestions. > > > + break; > > + case RTAS_FUNC_NOT_SUPPORTED: > > + ret = -EOPNOTSUPP; > > + break; > > + default: > > + ret = -EIO; > > + pr_err_ratelimited("unexpected ibm,receive-hvpipe-msg > > status %d\n", fwrc); > > + break; > > + } > > + > > + return ret; > > +} > > + > [...] > > Thanks, > -Mahesh.
