Hi, I am interested in intercepting task switches in vmx/svm in 64 bit mode with ept/npt enabled. However, I am not seeing the exit code due to task switch ( 9 for vmx and 125 for svm ) in the list of vm exits that I see in a typical guest run. I log the vm exit codes in the x86/svm.c:handle_exit method for svm and x86/vmx.c:vmx_handle_exit for vmx. Any pointers regarding this is very much appreciated. On a related note, does cr3 write interception approximate task switch interception ? ( I was able to intercept cr3 writes with svm while npt was enabled. but with vmx, I could intercept cr3 writes only with ept disabled ) Thanks, Leo Looking through the manuals, svm has a control bit in VMCS for enabling / disabling task switch interception while vmx does not seem to have such a control bit. ----------------------------------------- Excerpts from the manuals : Intel ------ Exit reason #9 indicates a vm exit due to task switch. Vol. 3C 24-9 : Some instructions cause VM exits regardless of the settings of the processor-based VM-execution controls (see Section 25.1.2), as do task switches (see Section 25.2). Vol. 3C 25-6 : Task switches. Task switches are not allowed in VMX non-root operation. Any attempt to effect a task switch in VMX non-root operation causes a VM exit. See Section 25.4.2 AMD ------- Intercept code to look for is: 7Dh VMEXIT_TASK_SWITCH task switch 15.14 AMD64 Technology Miscellaneous Intercepts : The SVM architecture includes intercepts to handle task switches, processor freezes due to FERR, and shutdown operations. Task switches can modify several resources that a VMM may want to protect (CR3, EFLAGS, LDT). However, instead of checking various intercepts (e.g., CR3 Write, LDTR Write) individually, task switches check only a single intercept bit. Page 581 : Layout of VMCB says Byte offset 00Ch : bit 29 Intercept task switches. ---------------------------------------- -- 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
