On Tue, Oct 8, 2013 at 8:18 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > Il 08/10/2013 15:03, Paolo Bonzini ha scritto: >> Il 08/10/2013 07:38, Kashyap Chamarthy ha scritto: >>> On Mon, Oct 7, 2013 at 6:29 PM, Kashyap Chamarthy <kashyap.cv@xxxxxxxxx> wrote: >>>> Gleb, so I just did a trace of KVM MMU to try to understand why L2 is >>>> stuck with shadow on EPT >>> >>> Paolo, were you able to reproduce this again? Yesterday, on #qemu you >>> mentioned you'll test it again :-) >> >> Yes, I could reproduce it too. >> >>>> Boot L2 guest: >> >> Here L2 doesn't go past the second instruction. It gets a page fault >> even though the spte is present, and KVM then loops on a page fault >> for 0xfe05b. >> >> Here is an annotated function_graph trace of L1. >> >> It's possible that L0 is injecting the same fault repeatedly, i.e. >> they are not different faults from the processor. I'll get an L0 >> trace next. >> > > The L0 trace is not particularly helpful (and probably would not be > particularly helpful even if there were a specific tracepoint for > VMREAD): > > 287.534156: kvm_exit: reason VMRESUME rip 0xffffffffa021f8d1 info 0 0 > 287.534160: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync > 287.534161: kvm_entry: vcpu 0 > 287.534162: kvm_exit: reason EXCEPTION_NMI rip 0xe05b info fe05b 80000b0e > 287.534170: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync > 287.534171: kvm_entry: vcpu 0 > 287.534172: kvm_exit: reason VMREAD rip 0xffffffffa021f97d info 0 0 > 287.534173: kvm_entry: vcpu 0 > 287.534174: kvm_exit: reason VMREAD rip 0xffffffffa021f996 info 0 0 > 287.534174: kvm_entry: vcpu 0 > 287.534175: kvm_exit: reason VMREAD rip 0xffffffffa021f9b5 info 0 0 > 287.534175: kvm_entry: vcpu 0 > 287.534177: kvm_exit: reason VMREAD rip 0xffffffffa021b377 info 0 0 > 287.534177: kvm_entry: vcpu 0 > 287.534178: kvm_exit: reason VMREAD rip 0xffffffffa021b5ce info 0 0 > 287.534179: kvm_entry: vcpu 0 > 287.534180: kvm_exit: reason VMREAD rip 0xffffffffa0222c95 info 0 0 > 287.534180: kvm_entry: vcpu 0 > 287.534181: kvm_exit: reason VMREAD rip 0xffffffffa0222e1c info 0 0 > 287.534182: kvm_entry: vcpu 0 > 287.534185: kvm_exit: reason MSR_READ rip 0xffffffff8104c2b6 info 0 0 > 287.534185: kvm_msr: msr_read 1d9 = 0x0 > 287.534185: kvm_entry: vcpu 0 > > And then it repeats: > > 287.534186: kvm_exit: reason VMRESUME rip 0xffffffffa021f8d1 info 0 0 > 287.534191: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 0sync > 287.534192: kvm_entry: vcpu 0 > > Trying to add function_graph loses a lot of events. > > Paolo Paolo, here's L0's trace with shadow-on-EPT. I invoked with the below command line on L0 $ /usr/bin/trace-cmd record -b 10000 -e kvmmmu then, started the L2 guest. Report: $ trace-cmd report 2>&1 | less The trace data file was large (150MB), just pasting the repeating message here: --------------------- . . . qemu-system-x86-2006 [000] 57931.272466: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272468: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272469: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272469: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272497: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272497: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272497: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272497: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272516: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272516: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272516: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272517: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272525: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272525: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272525: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272525: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272540: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272540: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272540: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272541: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272580: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272581: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272581: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272581: kvm_mmu_paging_element: pte 12001e1 level 2 qemu-system-x86-2006 [000] 57931.272593: kvm_mmu_pagetable_walk: addr ffffffff813d8404 pferr 10 F qemu-system-x86-2006 [000] 57931.272594: kvm_mmu_paging_element: pte 1c0f067 level 4 qemu-system-x86-2006 [000] 57931.272594: kvm_mmu_paging_element: pte 1c10063 level 3 qemu-system-x86-2006 [000] 57931.272594: kvm_mmu_paging_element: pte 12001e1 level 2 . . . . qemu-system-x86-2007 [000] 57967.047692: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047698: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047701: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047706: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047710: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047724: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047727: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047732: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047736: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3sync qemu-system-x86-2007 [000] 57967.047741: kvm_mmu_get_page: sp gfn 0 0/4 q0 direct --- !pge !nxe root 3s --------------------- /kashyap -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
