Messages in this thread |  | | Date | Fri, 25 Nov 2022 10:28:15 +0100 | Subject | Re: [PATCH v7 10/20] x86/virt/tdx: Use all system memory when initializing TDX module as TDX memory | From | David Hildenbrand <> |
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On 24.11.22 10:06, Huang, Kai wrote: > On Wed, 2022-11-23 at 17:50 -0800, Dan Williams wrote: >>> >>> @@ -968,6 +969,15 @@ int arch_add_memory(int nid, u64 start, u64 size, >>> unsigned long start_pfn = start >> PAGE_SHIFT; >>> unsigned long nr_pages = size >> PAGE_SHIFT; >>> >>> + /* >>> + * For now if TDX is enabled, all pages in the page allocator >>> + * must be TDX memory, which is a fixed set of memory regions >>> + * that are passed to the TDX module. Reject the new region >>> + * if it is not TDX memory to guarantee above is true. >>> + */ >>> + if (!tdx_cc_memory_compatible(start_pfn, start_pfn + nr_pages)) >>> + return -EINVAL; >> >> arch_add_memory() does not add memory to the page allocator. For >> example, memremap_pages() uses arch_add_memory() and explicitly does not >> release the memory to the page allocator. > > Indeed. Sorry I missed this. > >> This check belongs in >> add_memory_resource() to prevent new memory that violates TDX from being >> onlined. > > This would require adding another 'arch_cc_memory_compatible()' to the common > add_memory_resource() (I actually long time ago had such patch to work with the > memremap_pages() you mentioned above). > > How about adding a memory_notifier to the TDX code, and reject online of TDX > incompatible memory (something like below)? The benefit is this is TDX code > self contained and won't pollute the common mm code: > > +static int tdx_memory_notifier(struct notifier_block *nb, > + unsigned long action, void *v) > +{ > + struct memory_notify *mn = v; > + > + if (action != MEM_GOING_ONLINE) > + return NOTIFY_OK; > + > + /* > + * Not all memory is compatible with TDX. Reject > + * online of any incompatible memory. > + */ > + return tdx_cc_memory_compatible(mn->start_pfn, > + mn->start_pfn + mn->nr_pages) ? NOTIFY_OK : NOTIFY_BAD; > +} > + > +static struct notifier_block tdx_memory_nb = { > + .notifier_call = tdx_memory_notifier, > +};
With mhp_memmap_on_memory() some memory might already be touched during add_memory() (because part of the hotplug memory is used for holding the memmap), not when actually onlining memory. So in that case, this would be too late.
add_memory_resource() sounds better, even though I disgust such TDX special handling in common code.
-- Thanks,
David / dhildenb
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