On 20.06.2025 13:11, Roger Pau Monne wrote: > When not using CONFIG_BIGMEM there are some restrictions in the address > width for allocations of the domain structure, as it's PDX truncated to 32 > bits it's stashed into page_info structure for domain allocated pages. > > The current logic to calculate this limit is based on the internals of the > PDX compression used, which is not strictly required. Instead simplify the > logic to rely on the existing PDX to PFN conversion helpers used elsewhere. > > This has the added benefit of allowing alternative PDX compression > algorithms to be implemented without requiring to change the calculation of > the domain structure allocation boundary. > > As a side effect introduce pdx_to_paddr() conversion macro and use it. > > Signed-off-by: Roger Pau Monné <roger....@citrix.com>
Reviewed-by: Jan Beulich <jbeul...@suse.com> > @@ -498,14 +474,20 @@ struct domain *alloc_domain_struct(void) > * On systems with CONFIG_BIGMEM there's no packing, and so there's no > * such restriction. > */ > -#if defined(CONFIG_BIGMEM) || !defined(CONFIG_PDX_COMPRESSION) > - const unsigned int bits = IS_ENABLED(CONFIG_BIGMEM) ? 0 : > - 32 + PAGE_SHIFT; > +#if defined(CONFIG_BIGMEM) > + const unsigned int bits = 0; > #else > - static unsigned int __read_mostly bits; > + static unsigned int __ro_after_init bits; > > if ( unlikely(!bits) ) > - bits = _domain_struct_bits(); > + /* > + * Get the width for the next pfn, and unconditionally subtract one > + * from it to ensure the used width will not allocate past the PDX > + * field limit. > + */ > + bits = flsl(pdx_to_paddr(1UL << (sizeof_field(struct page_info, > + v.inuse._domain) * > 8))) You didn't like the slightly shorter sizeof(frame_table->v.inuse._domain) then? Jan
