Re: [PATCH v7 4/5] hw/mem/cxl-type3: Add CXL CDAT Data Object Exchange

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Thu, 13 Oct 2022 07:36:28 -0400
Gregory Price <gourry.memverge@gmail.com> wrote:

> Reading through your notes, everything seems reasonable, though I'm not
> sure I agree with the two pass notion, though I'll wait to see the patch
> set.
> 
> The enum is a good idea, *forehead slap*, I should have done it.  If we
> have a local enum, why not just make it global (within the file) and
> allocate the table as I have once we know how many MRs are present?

It's not global as we need the entries to be packed.  So if just one mr
(which ever one) the entries for that need to be at the beginning of
cdat_table.  I also don't want to bake into the outer caller that the
entries will always be the same size for different MRs.

For the two pass case...

I'll send code in a few mins, but in meantime my thought is that
the extended code for volatile + non volatile will looks something like:
(variable names made up)

	if (ct3d->volatile_mem) {
		volatile_mr = host_memory_backend_get_memory(ct3d->volatile_mem....);
		if (!volatile_mr) {
			return -ENINVAL;
		}
		rc = ct3_build_cdat_entries_for_mr(NULL, dsmad++, volatile_mr);
		if (rc < 0) {
			return rc;
		}
		volatile_len = rc;
	}

	if (ct3d->nonvolatile_mem) {
		nonvolatile_mr = host_memory_backend_get_memory(ct3d->nonvolatile_mem);
		if (!nonvolatile_mr) {
			return -ENINVAL;
		}
		rc = ct3_build_cdat_entries_for_mr(NULL, dmsmad++, nonvolatile_mr....);
		if (rc < 0) {
			return rc;
		}
		nonvolatile_len = rc;
	}

	dsmad = 0;

	table = g_malloc(0, (volatile_len + nonvolatile_len) * sizeof(*table));
	if (!table) {
		return -ENOMEM;
	}
	
	if (volatile_len) {
		rc = ct3_build_cdat_entries_for_mr(&table[0], dmsad++, volatile_mr....);
		if (rc < 0) {
			return rc;
		}
	}	
	if (nonvolatile_len) {
		rc = ct3_build_cdat_entries_for_mr(&table[volatile_len], dsmad++, nonvolatile_mr...);
		if (rc < 0) {
			/* Only place we need error handling.  Could make it more generic of course */
			for (i = 0; i < volatile_len; i++) {
				g_free(cdat_table[i]);
			}
			return rc;
		}
	}

	*cdat_table = g_steal_pointer(&table);


Jonathan

> 
> 6 eggs/half dozen though, I'm ultimately fine with either.
> 
> On Thu, Oct 13, 2022, 4:58 AM Jonathan Cameron <Jonathan.Cameron@huawei.com>
> wrote:
> 
> > On Wed, 12 Oct 2022 14:21:15 -0400
> > Gregory Price <gourry.memverge@gmail.com> wrote:
> >  
> > > Included in this response is a recommended patch set on top of this
> > > patch that resolves a number of issues, including style and a heap
> > > corruption bug.
> > >
> > > The purpose of this patch set is to refactor the CDAT initialization
> > > code to support future patch sets that will introduce multi-region
> > > support in CXL Type3 devices.
> > >
> > > 1) Checkpatch errors in the immediately prior patch
> > > 2) Flatting of code in cdat initialization
> > > 3) Changes in allocation and error checking for cleanliness
> > > 4) Change in the allocation/free strategy of CDAT sub-tables to simplify
> > >    multi-region allocation in the future.  Also resolves a heap
> > >    corruption bug
> > > 5) Refactor of CDAT initialization code into a function that initializes
> > >    sub-tables per memory-region.
> > >
> > > Gregory Price (5):
> > >   hw/mem/cxl_type3: fix checkpatch errors
> > >   hw/mem/cxl_type3: Pull validation checks ahead of functional code
> > >   hw/mem/cxl_type3: CDAT pre-allocate and check resources prior to work
> > >   hw/mem/cxl_type3: Change the CDAT allocation/free strategy
> > >   hw/mem/cxl_type3: Refactor CDAT sub-table entry initialization into a
> > >     function
> > >
> > >  hw/mem/cxl_type3.c | 240 +++++++++++++++++++++++----------------------
> > >  1 file changed, 122 insertions(+), 118 deletions(-)
> > >  
> >
> > Thanks, I'm going to roll this stuff into the original patch set for v8.
> > Some of this I already have (like the check patch stuff).
> > Some I may disagree with in which case  I'll reply to the patches - note
> > I haven't looked at them in detail yet!
> >
> > Jonathan
> >  
>