Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, Borislav Petkov wrote: > On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > > So much for the theory. That's not going to work. If the boot cpu has the > > feature then the alternatives will have been applied. So even if the flag > > mismatch can be observed

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, Borislav Petkov wrote: > On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > > So much for the theory. That's not going to work. If the boot cpu has the > > feature then the alternatives will have been applied. So even if the flag > > mismatch can be observed

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 14:54 +, Alan Cox wrote: > The only case I can think of where you'd get a non boot processor that > didn't have the same microcode loaded as the rest on entry to the OS would > be in a system where it was possibly to phyically hot plug processors > post boot. > > There

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 14:54 +, Alan Cox wrote: > The only case I can think of where you'd get a non boot processor that > didn't have the same microcode loaded as the rest on entry to the OS would > be in a system where it was possibly to phyically hot plug processors > post boot. > > There

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018 06:01:43 -0800 Arjan van de Ven wrote: > On 1/30/2018 5:11 AM, Borislav Petkov wrote: > > On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > >> So much for the theory. That's not going to work. If the boot cpu has the > >> feature then

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018 06:01:43 -0800 Arjan van de Ven wrote: > On 1/30/2018 5:11 AM, Borislav Petkov wrote: > > On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > >> So much for the theory. That's not going to work. If the boot cpu has the > >> feature then the alternatives will

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On 1/30/2018 5:11 AM, Borislav Petkov wrote: On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: So much for the theory. That's not going to work. If the boot cpu has the feature then the alternatives will have been applied. So even if the flag mismatch can be observed when a

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On 1/30/2018 5:11 AM, Borislav Petkov wrote: On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: So much for the theory. That's not going to work. If the boot cpu has the feature then the alternatives will have been applied. So even if the flag mismatch can be observed when a

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > So much for the theory. That's not going to work. If the boot cpu has the > feature then the alternatives will have been applied. So even if the flag > mismatch can be observed when a secondary CPU comes up the outcome will be >

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, Jan 30, 2018 at 01:57:21PM +0100, Thomas Gleixner wrote: > So much for the theory. That's not going to work. If the boot cpu has the > feature then the alternatives will have been applied. So even if the flag > mismatch can be observed when a secondary CPU comes up the outcome will be >

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, David Woodhouse wrote: > On Tue, 2018-01-30 at 12:37 +0100, Thomas Gleixner wrote: > > > In any case, if there is ucode mismatch between CPUs the whole thing is > > hosed anyway no matter what. So can you please agree on a solution so we > > can unbreak the current state of

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, David Woodhouse wrote: > On Tue, 2018-01-30 at 12:37 +0100, Thomas Gleixner wrote: > > > In any case, if there is ucode mismatch between CPUs the whole thing is > > hosed anyway no matter what. So can you please agree on a solution so we > > can unbreak the current state of

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 12:37 +0100, Thomas Gleixner wrote: > In any case, if there is ucode mismatch between CPUs the whole thing is > hosed anyway no matter what. So can you please agree on a solution so we > can unbreak the current state of affairs? If there is µcode mismatch between CPUs then

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 12:37 +0100, Thomas Gleixner wrote: > In any case, if there is ucode mismatch between CPUs the whole thing is > hosed anyway no matter what. So can you please agree on a solution so we > can unbreak the current state of affairs? If there is µcode mismatch between CPUs then

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, David Woodhouse wrote: > On Tue, 2018-01-30 at 12:18 +0100, Borislav Petkov wrote: > > On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > > > > > > I pondered that, but I didn't like it. I didn't want to always *force* > > > those features on, for all CPUs,

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 30 Jan 2018, David Woodhouse wrote: > On Tue, 2018-01-30 at 12:18 +0100, Borislav Petkov wrote: > > On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > > > > > > I pondered that, but I didn't like it. I didn't want to always *force* > > > those features on, for all CPUs,

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 12:18 +0100, Borislav Petkov wrote: > On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > > > > I pondered that, but I didn't like it. I didn't want to always *force* > > those features on, for all CPUs, just because they happened to be > > discovered at

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 12:18 +0100, Borislav Petkov wrote: > On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > > > > I pondered that, but I didn't like it. I didn't want to always *force* > > those features on, for all CPUs, just because they happened to be > > discovered at

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > I pondered that, but I didn't like it. I didn't want to always *force* > those features on, for all CPUs, just because they happened to be > discovered at boot time on the first CPU (which *did* have its > microcode updated by the

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, Jan 30, 2018 at 11:03:50AM +, David Woodhouse wrote: > I pondered that, but I didn't like it. I didn't want to always *force* > those features on, for all CPUs, just because they happened to be > discovered at boot time on the first CPU (which *did* have its > microcode updated by the

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 11:58 +0100, Borislav Petkov wrote: > > Does that help? > > diff --git a/arch/x86/kernel/cpu/intel.c > b/arch/x86/kernel/cpu/intel.c > index 6936d14d4c77..1dd596d0a6c4 100644 > --- a/arch/x86/kernel/cpu/intel.c > +++ b/arch/x86/kernel/cpu/intel.c > @@ -182,21 +182,21 @@

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Tue, 2018-01-30 at 11:58 +0100, Borislav Petkov wrote: > > Does that help? > > diff --git a/arch/x86/kernel/cpu/intel.c > b/arch/x86/kernel/cpu/intel.c > index 6936d14d4c77..1dd596d0a6c4 100644 > --- a/arch/x86/kernel/cpu/intel.c > +++ b/arch/x86/kernel/cpu/intel.c > @@ -182,21 +182,21 @@

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Mon, Jan 29, 2018 at 11:49:33PM +, David Woodhouse wrote: > Despite the fact that all the other code there seems to be doing it, > just using set_cpu_cap() in early_intel_init() doesn't actually work. > > When the CPU is queried again in identify_boot_cpu(), it all gets > overwritten

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Mon, Jan 29, 2018 at 11:49:33PM +, David Woodhouse wrote: > Despite the fact that all the other code there seems to be doing it, > just using set_cpu_cap() in early_intel_init() doesn't actually work. > > When the CPU is queried again in identify_boot_cpu(), it all gets > overwritten

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Mon, 29 Jan 2018, David Woodhouse wrote: > Despite the fact that all the other code there seems to be doing it, > just using set_cpu_cap() in early_intel_init() doesn't actually work. > > When the CPU is queried again in identify_boot_cpu(), it all gets > overwritten again. Do it in

Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

On Mon, 29 Jan 2018, David Woodhouse wrote: > Despite the fact that all the other code there seems to be doing it, > just using set_cpu_cap() in early_intel_init() doesn't actually work. > > When the CPU is queried again in identify_boot_cpu(), it all gets > overwritten again. Do it in

[PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

Despite the fact that all the other code there seems to be doing it, just using set_cpu_cap() in early_intel_init() doesn't actually work. When the CPU is queried again in identify_boot_cpu(), it all gets overwritten again. Do it in init_scattered_cpuid_features() instead. Turning the bits off

[PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel

Despite the fact that all the other code there seems to be doing it, just using set_cpu_cap() in early_intel_init() doesn't actually work. When the CPU is queried again in identify_boot_cpu(), it all gets overwritten again. Do it in init_scattered_cpuid_features() instead. Turning the bits off