> On Nov 25, 2017, at 9:50 AM, Thomas Gleixner <t...@linutronix.de> wrote: > > On Sat, 25 Nov 2017, Borislav Petkov wrote: >>> - >>> + wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + >>> 1), 0); >>> wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0); >> >> Right, so we have now two TSS thingies, AFAICT: >> >> tss = &per_cpu(cpu_tss, cpu); >> >> which is cpu_tss and then indirectly, we have also: >> >> &get_cpu_entry_area((cpu))->tss >> >> And those are two different things in my guest here: >> >> [ 0.044002] tss: 0xf5747000 >> [ 0.044706] entry area tss: 0xffef1000 >> >> What is the logic here? We carry two TSSs per CPU - one which is RO >> for the entry area and the other is the actual cpu_tss thing? Or am I >> misreading it? > > entry area tss is a alias mapping of cpu_tss > > + set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, tss), > + &per_cpu(cpu_tss, cpu), > + sizeof(struct tss_struct) / PAGE_SIZE, > + PAGE_KERNEL); >
Exactly. And, in the patch I haven't emailed, the alias is RO on x86_64. Maybe I should rename cpu_tss to cpu_tss_rw in that patch. > Thanks, > > tglx
