On Mon, Feb 09, 2026 at 11:41:02AM +0100, Alejandro Vallejo wrote: > It only has 2 callers, both of which can be conditionally removed. > > Signed-off-by: Alejandro Vallejo <[email protected]> > --- > I'd be ok conditionalising the else branch on... > > IS_ENABLED(CONFIG_SHADOW_PAGING )|| IS_ENABLED(CONFIG_LOG_DIRTY) > > logdirty patch: > https://lore.kernel.org/xen-devel/[email protected] > > ... to avoid the danger of stale pointers, with required changes elsewhere so > none.c is only compiled out in that case. > > I'm not sure how much it matters seeing how they are all unreachable. > --- > xen/arch/x86/mm/Makefile | 2 +- > xen/arch/x86/mm/paging.c | 4 +- > xen/arch/x86/mm/shadow/Makefile | 4 -- > xen/arch/x86/mm/shadow/none.c | 77 --------------------------------- > 4 files changed, 3 insertions(+), 84 deletions(-) > delete mode 100644 xen/arch/x86/mm/shadow/none.c > > diff --git a/xen/arch/x86/mm/Makefile b/xen/arch/x86/mm/Makefile > index 960f6e8409..066c4caff3 100644 > --- a/xen/arch/x86/mm/Makefile > +++ b/xen/arch/x86/mm/Makefile > @@ -1,4 +1,4 @@ > -obj-y += shadow/ > +obj-$(CONFIG_SHADOW_PAGING) += shadow/ > obj-$(CONFIG_HVM) += hap/ > > obj-$(CONFIG_ALTP2M) += altp2m.o > diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c > index 2396f81ad5..5f70254cec 100644 > --- a/xen/arch/x86/mm/paging.c > +++ b/xen/arch/x86/mm/paging.c > @@ -634,7 +634,7 @@ int paging_domain_init(struct domain *d) > */ > if ( hap_enabled(d) ) > hap_domain_init(d); > - else > + else if ( IS_ENABLED(CONFIG_SHADOW_PAGING) ) > rc = shadow_domain_init(d);
If you want to go this route you will need to set rc = -EOPNOTSUPP; prior to the `if ... else if` on the HVM case. Otherwise when shadow is compiled out, and the toolstack has not specified the HAP flag at domain creation you will end up with a domain that doesn't have the paging operations initialized as paging_domain_init() would return 0 with neither HAP nor shadow having been setup. That's likely to trigger NULL pointer dereferences inside of Xen. Also, seeing the code in arch_sanitise_domain_config() we possibly want to return an error at that point if toolstack attempts to create an HVM guest without HAP enabled, and shadow is build time disabled. I've sent a patch to that end. Thanks, Roger.
