Hi Avi, I find that the qemu processor reset state is not per the IA32 processor specifications. (Sections 8.1.1 of http://www.intel.com/Assets/PDF/manual/253668.pdf) In qemu-kvm.git in file target-i386/helper.c in function cpu_reset the segment registers are initialized as follows: cpu_x86_load_seg_cache(env, R_CS, 0xf000, 0xffff0000, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_CS_MASK | DESC_R_MASK); cpu_x86_load_seg_cache(env, R_DS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); cpu_x86_load_seg_cache(env, R_ES, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); cpu_x86_load_seg_cache(env, R_SS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); cpu_x86_load_seg_cache(env, R_FS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); cpu_x86_load_seg_cache(env, R_GS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); While the IA32 cpu reset state specification says that Segment Accessed bit is also 1 at the time of cpu reset. so the above code should look like this: cpu_x86_load_seg_cache(env, R_CS, 0xf000, 0xffff0000, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_CS_MASK | DESC_R_MASK | DESC_A_MASK); cpu_x86_load_seg_cache(env, R_DS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK | DESC_A_MASK); cpu_x86_load_seg_cache(env, R_ES, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK| DESC_A_MASK); cpu_x86_load_seg_cache(env, R_SS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK |DESC_A_MASK); cpu_x86_load_seg_cache(env, R_FS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); cpu_x86_load_seg_cache(env, R_GS, 0, 0, 0xffff, DESC_P_MASK | DESC_S_MASK | DESC_W_MASK); This discrepancy is adding the need of the following function in the unrestricted guest patch. +static inline u32 get_segment_ar(int seg) +{ + if (!enable_unrestricted_guest) + return 0xf3; + + switch (seg) { + case VCPU_SREG_CS: + return 0x9b; + case VCPU_SREG_TR: + return 0x8b; + case VCPU_SREG_LDTR: + return 0x82; + default: + return 0x93; + } +} + For the unrestricted guest support either we can fix this discrepancy in the qemu code, or have a functionality like get_segment_ar() in the kvm vmx code. what do you suggest ? Thanks & Regards, Nitin -- 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
