Messages in this thread | | | Date | Mon, 20 Aug 2018 18:24:50 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86/spectre: Expand test for vulnerability to empty RSB exploits |
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On Mon, 20 Aug 2018, Jim Mattson wrote: > On Mon, Aug 20, 2018 at 9:00 AM, Thomas Gleixner <tglx@linutronix.de> wrote: > > > > On Tue, 7 Aug 2018, Jim Mattson wrote: > > > > > Skylake-era Intel CPUs are vulnerable to exploits of empty RSB > > > conditions. On hardware, platform vulnerability can be determined > > > simply by checking the processor's DisplayModel/DisplayFamily > > > signature. However, when running in a VM, the operating system should > > > also query IA32_ARCH_CAPABILITIES.RSBA[bit 2], a synthetic bit that > > > can be set by a hypervisor to indicate that the VM might run on a > > > vulnerable physical processor, regardless of the > > > DisplayModel/DisplayFamily reported by CPUID. > > > > > > Note that IA32_ARCH_CAPABILITIES.RSBA[bit 2] is always clear on > > > hardware, so the DisplayModel/DisplayFamily check is still required. > > > > > > For all of the details, see the Intel white paper, "Retpoline: A > > > Branch Target Injection Mitigation" (document number 337131-001), > > > section 5.3: Virtual Machine CPU Identification. > > > > > > Signed-off-by: Jim Mattson <jmattson@google.com> > > > Reviewed-by: Peter Shier <pshier@google.com> > > > > That has been superseeded by: > > > > fdf82a7856b3 ("x86/speculation: Protect against userspace-userspace spectreRSB") > > > > right? At least it does not apply anymore... > > Right. It doesn't appear that Skylake CPUs get any special treatment any more.
Yeah, it's universally f*cked up by now.
Thanks,
tglx
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