On Mon, Aug 20, 2018 at 05:11:53PM -0500, Brijesh Singh wrote: > Hi All, > > The following commit > > " > x86/kvmclock: Remove memblock dependency > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=368a540e0232ad446931f5a4e8a5e06f69f21343 > > " > broke the SEV support in 4.18. > > Since the guest physical address holding the wall_clock and > vcpu_time_info are shared with the hypervisor it must be mapped > as "decrypted" when SEV is active. To clear the C-bit we use > kernel_physical_mapping_init() to split the large pages into 4K before > changing the C-bit. Now the kernel_physical_mapping_init() is failing to > allocate the memory because its called very early. > > [ 0.000000] Call Trace: > [ 0.000000] ? dump_stack+0x5c/0x80 > [ 0.000000] ? panic+0xe7/0x247 > [ 0.000000] ? alloc_low_pages+0x130/0x130 > [ 0.000000] ? kernel_physical_mapping_init+0xe0/0x204 > [ 0.000000] ? early_set_memory_enc_dec+0x123/0x174 > [ 0.000000] ? 0xffffffffae000000 > [ 0.000000] ? kvmclock_init+0x60/0x1ea > [ 0.000000] ? kvm_init_platform+0xa/0x16 > [ 0.000000] ? setup_arch+0x434/0xce9 > [ 0.000000] ? start_kernel+0x67/0x52e > [ 0.000000] ? load_ucode_bsp+0x76/0x12e > [ 0.000000] ? secondary_startup_64+0xa4/0xb0 Silly question: can we delay the call to kernel_physical_mapping_init() to right before those variables are accessed by the guest for the first time, assuming we can allocate memory at that point? -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --
