Hi Julien
> -----Original Message-----
> From: Julien Grall <jul...@xen.org>
> Sent: Friday, August 13, 2021 9:12 PM
> To: Penny Zheng <penny.zh...@arm.com>; xen-devel@lists.xenproject.org;
> sstabell...@kernel.org
> Cc: Bertrand Marquis <bertrand.marq...@arm.com>; Wei Chen
> <wei.c...@arm.com>; nd <n...@arm.com>
> Subject: Re: [PATCH V4 09/10] xen/arm: check "xen,static-mem" property
> during domain construction
>
> Hi,
>
> On 28/07/2021 11:27, Penny Zheng wrote:
> > This commit checks "xen,static-mem" device tree property in /domUx
> > node, to determine whether domain is on Static Allocation, when
> > constructing domain during boot-up.
> >
> > Right now, the implementation of allocate_static_memory is missing,
> > and will be introduced later. It just BUG() out at the moment.
>
> I think the code is small enough to fold it in patch #10. In fact...
>
Ok. I'll combine.
> >
> > Signed-off-by: Penny Zheng <penny.zh...@arm.com>
> > ---
> > xen/arch/arm/domain_build.c | 37
> ++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 36 insertions(+), 1 deletion(-)
> >
> > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > index 6c86d52781..cdb16f2086 100644
> > --- a/xen/arch/arm/domain_build.c
> > +++ b/xen/arch/arm/domain_build.c
> > @@ -2425,6 +2425,37 @@ static int __init construct_domU(struct domain *d,
> > struct kernel_info kinfo = {};
> > int rc;
> > u64 mem;
> > + const struct dt_property *static_mem_prop;
> > + u32 static_mem_addr_cells, static_mem_size_cells;
> > + bool static_mem = false;
>
> You don't need those information outside of allocate_static_memory(). So I
> think it would be best to move the code in that function.
>
Sure.
> > +
> > + /*
> > + * Guest RAM could be static memory which will be specified through
> > + * "xen,static-mem" property.
> > + */
> > + static_mem_prop = dt_find_property(node, "xen,static-mem", NULL);
> > + if ( static_mem_prop )
> > + {
> > + static_mem = true;
> > +
> > + if ( !dt_property_read_u32(node, "#xen,static-mem-address-cells",
> > + &static_mem_addr_cells) )
> > + {
> > + printk("Error building DomU: cannot read "
> > + "\"#xen,static-mem-address-cells\" property\n");
> We don't split comment over multi-line (even they are more than 80
> characters). This is to help grep message in the code.
>
> Although for this one I would replaced "Error building Domu:" with simply
> with the domain ID (you can use %pd and 'd'). The caller will then print there
> was an error during building.
>
Thanks for the explanation, learned.
>
> > + return -EINVAL;
> > + }
> > +
> > + if ( !dt_property_read_u32(node, "#xen,static-mem-size-cells",
> > + &static_mem_size_cells) )
> > + {
> > + printk("Error building DomU: cannot read "
> > + "\"#xen,static-mem-size-cells\" property\n");
>
> My remark applies here as well.
>
> > + return -EINVAL;
> > + }
> > +
> > + BUG_ON(static_mem_size_cells > 2 || static_mem_addr_cells >
> > + 2);
>
> Did we validate the DT before hand? If not, then I think
>
Yeah... I think I did the check in first parse. It's redundant.
> > + }
>
>
> >
> > rc = dt_property_read_u64(node, "memory", &mem);
> > if ( !rc )
> > @@ -2452,7 +2483,11 @@ static int __init construct_domU(struct domain *d,
> > /* type must be set before allocate memory */
> > d->arch.type = kinfo.type;
> > #endif
> > - allocate_memory(d, &kinfo);
> > + if ( !static_mem )
>
> With my suggestion above, the check can be replaced with:
>
> if ( !dt_find_property(node, "xen,static-mem", NULL) )
>
Sure, That’s more simple.
> > + allocate_memory(d, &kinfo);
> > + else
> > + /* TODO: allocate_static_memory(...). */
> > + BUG();
> >
> > rc = prepare_dtb_domU(d, &kinfo);
> > if ( rc < 0 )
> >
>
> Cheers,
>
> --
Cheers
--
Penny
> Julien Grall
