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>> >> + v->arch.hvm.guest_cr[0] = vmcb_get_cr0(vmcb); >> v->arch.hvm.guest_cr[2] = vmcb_get_cr2(vmcb); >> if ( paging_mode_hap(v->domain) ) >> v->arch.hvm.guest_cr[3] = v->arch.hvm.hw_cr[3] = vmcb_get_cr3(vmcb); > gitlab-CI says no to this patch [1], and I think it's the change above which > gets in the way of running guests in shadow mode (as is the case for the two > qemu-smoke-x86_64-*-pvh tests). svm_update_guest_cr() has > > value = v->arch.hvm.guest_cr[0]; > if ( paging_mode_shadow(v->domain) ) > value |= X86_CR0_PG | X86_CR0_WP; > vmcb_set_cr0(vmcb, value); > > i.e. upon reading back the guest's CR0 value we would wrongly record it > having PG (and WP) enabled, at which point shadow code would try to use the > still-zero CR3 as page table base. I think values need merging here, with > only TS and MP taken from what vmcb_get_cr0() returns. Yes this is broken for Shadow. Shadow shouldn't be trying to use CR0_WRITE_SEL.  What's in the VMCB is unrelated to the guest's choice of value, and reverse engineering it is fragile. Use full CR0_WRITE for Shadow guests, and use CR0_WRITE_SEL for HAP only. ~Andrew