https://bugzilla.kernel.org/show_bug.cgi?id=45931 Summary: Nested Virt: VMX can't be initialized in L1 Xen ("Xen on KVM") Product: Virtualization Version: unspecified Kernel Version: 3.6-RC1 Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm AssignedTo: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx ReportedBy: yongjie.ren@xxxxxxxxx CC: avi@xxxxxxxxxx Regression: No Created an attachment (id=77661) --> (https://bugzilla.kernel.org/attachment.cgi?id=77661) xl-dmesg-in-L1-Xen.log Hi folks, I did some basic testing on nested virtualization on Intel x86-64 platform. Will KVM support Xen as L1 guest in nested virtualization ? When I tried "Xen on KVM" mode, I found VMX can't be initialized in L1 Xen hypervisor. I tried both "-cpu host" and "-cpu qemu64,+vmx" parameters in qemu-kvm command line. -------some log in 'xl dmesg' command line in L1 Xen --- (XEN) VMX: CPU0 has insufficent CPU-Based Exec Control (b299868c but requires min 2299968c) (XEN) VMX: CPU0 has insufficent VMExit Control (00000200 but requires min 00008200) (XEN) VMX: failed to initialise. ------more details in the attached "xl-dmesg-L1.log"---- In Xen source code, I found the following related to the mentioned error. "xen-unstable.hg/xen/include/asm-x86/hvm/vmx/vmcs.h" #define CPU_BASED_RDTSC_EXITING 0x00001000 #define VM_EXIT_ACK_INTR_ON_EXIT 0x00008000 ---- Avi confirmed there're two issues, and fixed 1st one (RDTSC) by the following patch. All processors that support VMX have that feature, and guests (Xen) depend on it. As we already implement it, advertize it to the guest. Signed-off-by: Avi Kivity <avi@xxxxxxxxxx> --- arch/x86/kvm/vmx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index cc8ad98..8092f25 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -1990,7 +1990,7 @@ static __init void nested_vmx_setup_ctls_msrs(void) #endif CPU_BASED_MOV_DR_EXITING | CPU_BASED_UNCOND_IO_EXITING | CPU_BASED_USE_IO_BITMAPS | CPU_BASED_MONITOR_EXITING | - CPU_BASED_RDPMC_EXITING | + CPU_BASED_RDPMC_EXITING | CPU_BASED_RDTSC_EXITING | CPU_BASED_ACTIVATE_SECONDARY_CONTROLS; /* * We can allow some features even when not supported by the -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- 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
