On Wed, Apr 03, 2024 at 04:08:35PM -0500, Kalra, Ashish wrote: > > On 4/2/2024 5:42 PM, Michael Roth wrote: > >On Tue, Apr 02, 2024 at 05:31:09PM -0500, Kalra, Ashish wrote: > >>On 4/2/2024 5:09 PM, Tom Lendacky wrote: > >>>On 3/12/24 13:47, Ashish Kalra wrote: > >>>>From: Ashish Kalra <ashish.kalra@xxxxxxx> > >>>> > >>>>RMP table start and end physical range may not be aligned to 2MB in > >>>>the e820 tables causing fatal RMP page faults during kexec boot when > >>>>new page allocations are done in the same 2MB page as the RMP table. > >>>>Check if RMP table start and end physical range in e820_table is not > >>>>aligned to 2MB and in that case use e820__range_update() to map this > >>>>range to reserved. > >>>> > >>>>Override e820__memory_setup_default() to check and apply these RMP table > >>>>fixups in e820_table before e820_table is used to setup > >>>>e280_table_firmware and e820_table_kexec. > >>>> > >>>>Fixes: c3b86e61b756 ("x86/cpufeatures: Enable/unmask SEV-SNP CPU > >>>>feature") > >>>>Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> > >>>>--- > >>>> arch/x86/virt/svm/sev.c | 52 +++++++++++++++++++++++++++++++++++++++++ > >>>> 1 file changed, 52 insertions(+) > >>>> > >>>>diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c > >>>>index cffe1157a90a..e0d7584df28f 100644 > >>>>--- a/arch/x86/virt/svm/sev.c > >>>>+++ b/arch/x86/virt/svm/sev.c > >>>>@@ -65,6 +65,8 @@ static u64 probed_rmp_base, probed_rmp_size; > >>>> static struct rmpentry *rmptable __ro_after_init; > >>>> static u64 rmptable_max_pfn __ro_after_init; > >>>> +static char *__init snp_rmptable_e820_fixup(void); > >>>>+ > >>>> static LIST_HEAD(snp_leaked_pages_list); > >>>> static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); > >>>> @@ -160,9 +162,59 @@ bool snp_probe_rmptable_info(void) > >>>> pr_info("RMP table physical range [0x%016llx - 0x%016llx]\n", > >>>> probed_rmp_base, probed_rmp_base + probed_rmp_size - 1); > >>>> + /* > >>>>+ * Override e820__memory_setup_default() to do any RMP table fixups > >>>>+ * for kexec if required. > >>>>+ */ > >>>>+ x86_init.resources.memory_setup = snp_rmptable_e820_fixup; > >>>This produces a build warning: > >>> > >>>WARNING: modpost: vmlinux: section mismatch in reference: > >>>snp_probe_rmptable_info+0x95 (section: .text) -> x86_init (section: > >>>.init.data) > >>>WARNING: modpost: vmlinux: section mismatch in reference: > >>>snp_probe_rmptable_info+0x99 (section: .text) -> snp_rmptable_e820_fixup > >>>(section: .init.text) > >>> > >>Oh, so this requires snp_probe_rmptable_info() to be fixed to use the __init > >>macro. > >> > >>I believe that snp_probe_rmptable_info() should be anyway using the __init > >>macro and this fix for snp_probe_rmptable_info() needs to be sent as a > >>separate patch and regardless of this patch getting merged or not. > >I think you'll hit issues with: > > > > bsp_determine_snp() -> //non-__init > > snp_probe_rmptable_info() //__init > > > >and bsp_determine_snp() sticks around as a function pointer assigned to > >cpuinfo_x86 so I don't think you can use __init there. > > > >So might need to just drop __init from snp_rmptable_e820_fixup(). > > Actually, that will not help as snp_probe_rmptable_info() is *also* > accessing x86_init.resources.memory_setup > What if we flipped the whole flow? Borislav is adding a CC_ATTR to indicate HOST_SEV_SNP support, we don't need to clear X86_FEATURE_SEV_SNP at this phase (or at all for that matter). snp_probe_rmptable_info() can be done later during kernel init, once e820 has been parsed. One way of doing this would be to override x86_init.resources.memory_setup() to do both snp_probe_rmptable_info() and snp_rmptable_e820_fixup(). What do you think?