On 5.12.24 г. 9:57 ч., Mike Rapoport wrote:
Hi,
I've been auditing for_each_mem_pfn_range() users and it's usage in TDX is
dubious for me.
On Fri, Nov 10, 2023 at 12:55:45AM +1300, Kai Huang wrote:
As TDX-usable memory is a fixed configuration, take a snapshot of the
memory configuration from memblocks at the time of module initialization
(memblocks are modified on memory hotplug). This snapshot is used to
AFAUI this could happen long after free_initmem() which discards all
memblock data on x86.
> >> enable TDX support for *this* memory configuration only. Use a memory
hotplug notifier to ensure that no other RAM can be added outside of
this configuration.
...
+/*
+ * Ensure that all memblock memory regions are convertible to TDX
+ * memory. Once this has been established, stash the memblock
+ * ranges off in a secondary structure because memblock is modified
+ * in memory hotplug while TDX memory regions are fixed.
+ */
+static int build_tdx_memlist(struct list_head *tmb_list)
+{
+ unsigned long start_pfn, end_pfn;
+ int i, ret;
+
+ for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
Unles ARCH_KEEP_MEMBLOCK is defined this won't work after free_initmem()
TDX_HOST actually selects ARCH_KEEP_MEMBLOCK:
6 config INTEL_TDX_HOST
5 bool "Intel Trust Domain Extensions (TDX) host support"
4 depends on CPU_SUP_INTEL
3 depends on X86_64
2 depends on KVM_INTEL
1 depends on X86_X2APIC
1980 select ARCH_KEEP_MEMBLOCK
1 depends on CONTIG_ALLOC
2 depends on !KEXEC_CORE
3 depends on X86_MCE
<snip>
