Hi Paolo, As suggested by You, the following is the issue info. Is this something to be fixed in host kernel?
Description: FreeBSD 64bit(10.0) Guest freezes at "booting...." on Linux KVM, host running RHEL6.4 or RHEL 6.5. Tested various versions of FreeBSD, Any version of FreeBSD 64bit will freeze the same way. The issue occurs only on RHEL6.4 or RHEL6.5 host, if the Physical CPU has "SMEP" feature enabled. In these host versions, if the kernel loaded with "nosmep" boot parameter, cannot find "SMEP" feature on '/proc/cpuinfo', And FreeBSD guest boots properly. The issue does not happen in other distributions like Fedora or Ubuntu. Hardware: model name : Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz The searches on "SMEP" fixes led us to " https://github.com/torvalds/linux/commit/c08800a56cb8622bb61577abb4a12"; The trace on host while the Guest froze with "SMEP" feature enabled qemu-kvm-13546 [002] 345536.613350: kvm_entry: vcpu 0 qemu-kvm-13546 [002] 345536.613351: kvm_exit: [FAILED TO PARSE] exit_reason=48 guest_rip=0xffffffff80cfdac8 qemu-kvm-13546 [002] 345536.613351: kvm_page_fault: address b0000 error_code 181 qemu-kvm-13546 [002] 345536.613352: kvm_mmu_pagetable_walk: addr ffffffff80cfdac8 pferr 10 F qemu-kvm-13546 [002] 345536.613352: kvm_mmu_paging_element: pte 42027 level 4 qemu-kvm-13546 [002] 345536.613352: kvm_mmu_paging_element: pte 43027 level 3 qemu-kvm-13546 [002] 345536.613352: kvm_mmu_paging_element: pte c000a7 level 2 qemu-kvm-13546 [002] 345536.613353: kvm_mmu_walker_error: pferr 11 P|F The trace on host while Guest booted properly with "nosmep", SMEP feature disabled qemu-kvm-10650 [007] 438.163157: kvm_entry: vcpu 0 qemu-kvm-10650 [007] 438.163160: kvm_exit: [FAILED TO PARSE] exit_reason=48 guest_rip=0xffffffff80cfdac8 qemu-kvm-10650 [007] 438.163160: kvm_page_fault: address b8000 error_code 181 qemu-kvm-10650 [007] 438.163162: kvm_mmu_pagetable_walk: addr ffffffff80cfdac8 pferr 10 F qemu-kvm-10650 [007] 438.163163: kvm_mmu_paging_element: pte 42027 level 4 qemu-kvm-10650 [007] 438.163163: kvm_mmu_paging_element: pte 43027 level 3 qemu-kvm-10650 [007] 438.163163: kvm_mmu_paging_element: pte c000a7 level 2 qemu-kvm-10650 [007] 438.163164: kvm_mmu_pagetable_walk: addr ffffffff800b8000 pferr 0 qemu-kvm-10650 [007] 438.163165: kvm_mmu_paging_element: pte 42027 level 4 qemu-kvm-10650 [007] 438.163165: kvm_mmu_paging_element: pte 43027 level 3 qemu-kvm-10650 [007] 438.163165: kvm_mmu_paging_element: pte e7 level 2 qemu-kvm-10650 [007] 438.163166: kvm_mmu_pagetable_walk: addr ffffffff800b8000 pferr 0 Thanks, Venkatesh -----Original Message----- From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo Bonzini Sent: Thursday, September 25, 2014 6:44 PM To: Ramanjaneyulu Talla Cc: dongxiao xu; xiantao zhang; g...@redhat.com; mtosa...@redhat.com; Bill Chuan; Venkateswara Rao Nandigam Subject: Re: Query Il 25/09/2014 07:15, Ramanjaneyulu Talla ha scritto: > Hi Paola, > > Thanks for your response. Even we tried disabling SMEP bit in CR4 > register in FreeBSD VM and didn¹t help. Interesting thing is, when we > run 64-bit Linux guest on same environment, its working fine. It means > this issue is fixed in Linux and we are trying to understand how it got fixed. This issue affect Linux hosts, not Linux guests. I don't think Linux guests try to use SMEP in non-paging mode. Please use the upstream mailing list and include: - a description of the problem - the hardware you're using - what led you to c08800a56cb8622bb61577abb4a120c6 - possibly, a trace of the FreeBSD guest obtained as in http://www.linux-kvm.org/page/Tracing (but with "trace-cmd record -b 20000 -e kvm -e kvmmmu"). > Are you suggesting to disable SMAP also along with SMEP as a fix? No, SMAP is not available on most current hardware. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
