Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed 2019-08-28 16:15:06, Thomas Gleixner wrote: > On Wed, 28 Aug 2019, Pavel Machek wrote: > > On Wed 2019-08-28 14:46:21, Borislav Petkov wrote: > > > On Wed, Aug 28, 2019 at 02:29:13PM +0200, Pavel Machek wrote: > > > > This is not a way to have an inteligent conversation. > > > > > > No, this *is* the way to keep the conversation sane, without veering > > > off into some absurd claims. > > > > > > So, to cut to the chase: you can simply add "rdrand=force" to your > > > cmdline parameters and get back to using RDRAND. > > > > > > And yet if you still feel this fix does not meet your expectations, > > > you were told already to either produce patches or who to contact. I'm > > > afraid complaining on this thread won't get you anywhere but that's your > > > call. > > > > No, this does not meet my expectations, it violates stable kernel > > rules, and will cause regression to some users, while better solution > > is known to be available. > > Your unqualified ranting does not meet my expectation either and it > violates any rule of common sense. > > For the record: > > Neither AMD nor we have any idea which particular machines have a fixed > BIOS and which have not. There is no technical indicator either at boot > time as the wreckage manifests itself only after resume. > > So in the interest of users the only sensible decision is to disable > RDRAND for this class of CPUs. No. Obviously best solution would be microcode update to fix the problem, or to enable kernel to fix the problem. > If you have a list of machines which have a fixed BIOS, then provide it > in form of patches. If not then stop claiming that there is a better > solution available. And yes, whitelist would be already better than present solution. It is not my duty to submit fixes to your proposed patch. > Anyway, I'm done with that and further rants of yours go directly to > /dev/null. > > Thanks for wasting everyones time Thanks for your profesional attitude. Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed, 28 Aug 2019, Pavel Machek wrote: > On Wed 2019-08-28 14:46:21, Borislav Petkov wrote: > > On Wed, Aug 28, 2019 at 02:29:13PM +0200, Pavel Machek wrote: > > > This is not a way to have an inteligent conversation. > > > > No, this *is* the way to keep the conversation sane, without veering > > off into some absurd claims. > > > > So, to cut to the chase: you can simply add "rdrand=force" to your > > cmdline parameters and get back to using RDRAND. > > > > And yet if you still feel this fix does not meet your expectations, > > you were told already to either produce patches or who to contact. I'm > > afraid complaining on this thread won't get you anywhere but that's your > > call. > > No, this does not meet my expectations, it violates stable kernel > rules, and will cause regression to some users, while better solution > is known to be available. Your unqualified ranting does not meet my expectation either and it violates any rule of common sense. For the record: Neither AMD nor we have any idea which particular machines have a fixed BIOS and which have not. There is no technical indicator either at boot time as the wreckage manifests itself only after resume. So in the interest of users the only sensible decision is to disable RDRAND for this class of CPUs. If you have a list of machines which have a fixed BIOS, then provide it in form of patches. If not then stop claiming that there is a better solution available. Anyway, I'm done with that and further rants of yours go directly to /dev/null. Thanks for wasting everyones time tglx
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed 2019-08-28 14:46:21, Borislav Petkov wrote: > On Wed, Aug 28, 2019 at 02:29:13PM +0200, Pavel Machek wrote: > > This is not a way to have an inteligent conversation. > > No, this *is* the way to keep the conversation sane, without veering > off into some absurd claims. > > So, to cut to the chase: you can simply add "rdrand=force" to your > cmdline parameters and get back to using RDRAND. > > And yet if you still feel this fix does not meet your expectations, > you were told already to either produce patches or who to contact. I'm > afraid complaining on this thread won't get you anywhere but that's your > call. No, this does not meet my expectations, it violates stable kernel rules, and will cause regression to some users, while better solution is known to be available. Best regards, Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed, Aug 28, 2019 at 02:29:13PM +0200, Pavel Machek wrote: > This is not a way to have an inteligent conversation. No, this *is* the way to keep the conversation sane, without veering off into some absurd claims. So, to cut to the chase: you can simply add "rdrand=force" to your cmdline parameters and get back to using RDRAND. And yet if you still feel this fix does not meet your expectations, you were told already to either produce patches or who to contact. I'm afraid complaining on this thread won't get you anywhere but that's your call. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed 2019-08-28 14:16:28, Borislav Petkov wrote: > On Wed, Aug 28, 2019 at 02:09:36PM +0200, Pavel Machek wrote: > > Yes, and now AMD has patch to break it on *all* machines. > > It doesn't break all machines - you need to look at that patch again. This is not a way to have an inteligent conversation. The patch clearly breaks more machines than it has to. It is known to cause regression. You snipped the rest of the email with better ways to solve this. Best regards, Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed, Aug 28, 2019 at 02:09:36PM +0200, Pavel Machek wrote: > Yes, and now AMD has patch to break it on *all* machines. It doesn't break all machines - you need to look at that patch again. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed 2019-08-28 14:00:24, Borislav Petkov wrote: > On Wed, Aug 28, 2019 at 01:49:47PM +0200, Pavel Machek wrote: > > AMD screwed this up, > > Except that it wasn't AMD who screwed up but BIOS on *some* laptops. Yes, and now AMD has patch to break it on *all* machines. Hmm. "Get random data" instruction that fails to return random data, depending on BIOS... (and even indicates success, IIRC)... Sounds like CPU vendor screwup to me. And they can also fix it up. If re-initing random generator is impossible from kernel, surely CPU microcode can be either updated to do the init automatically, or at least allow kernel to do the init. Best regards, Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Wed, Aug 28, 2019 at 01:49:47PM +0200, Pavel Machek wrote: > AMD screwed this up, Except that it wasn't AMD who screwed up but BIOS on *some* laptops. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
Hi! > > > There is no way to reinitialize RDRAND from the kernel otherwise we would > > > have exactly done that. If you know how to do that please tell. > > > > Would they? AMD is not exactly doing good job with communication > > Yes they would. Stop making up weird conspiracy theories. > > here. If BIOS can do it, kernel can do it, too... > > May I recommend to read up on SMM and BIOS being able to lock down access > to certain facilities? > > > or do you have information saying otherwise? > > Yes. It was clearly stated by Tom that it can only be done in the > BIOS. Do you have a link for that? Because I don't think I seen that one. > > > Also disabling it for every BIOS is the only way which can be done because > > > there is no way to know whether the BIOS is fixed or not at cold boot > > > time. And it has to be known there because applications cache the > > > > I'm pretty sure DMI-based whitelist would help here. It should be > > reasonably to fill it with the common machines at least. > > Send patches to that effect. Why should it be my job? AMD screwed this up, they should fix it properly. And you should insist on proper fix. > > Plus, where is the CVE, and does AMD do anything to make BIOS vendors > > fix them? > > May I redirect you to: https://www.amd.com/en/corporate/contact That will certainly make communication easier, right. Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
Pavel, On Wed, 28 Aug 2019, Pavel Machek wrote: > On Tue 2019-08-27 15:30:30, Thomas Gleixner wrote: > > There is no way to reinitialize RDRAND from the kernel otherwise we would > > have exactly done that. If you know how to do that please tell. > > Would they? AMD is not exactly doing good job with communication Yes they would. Stop making up weird conspiracy theories. > here. If BIOS can do it, kernel can do it, too... May I recommend to read up on SMM and BIOS being able to lock down access to certain facilities? > or do you have information saying otherwise? Yes. It was clearly stated by Tom that it can only be done in the BIOS. > > Also disabling it for every BIOS is the only way which can be done because > > there is no way to know whether the BIOS is fixed or not at cold boot > > time. And it has to be known there because applications cache the > > I'm pretty sure DMI-based whitelist would help here. It should be > reasonably to fill it with the common machines at least. Send patches to that effect. > Plus, where is the CVE, and does AMD do anything to make BIOS vendors > fix them? May I redirect you to: https://www.amd.com/en/corporate/contact Thanks, tglx
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Tue 2019-08-27 15:30:30, Thomas Gleixner wrote: > On Tue, 27 Aug 2019, Pavel Machek wrote: > > > On Tue 2019-08-27 09:50:51, Greg Kroah-Hartman wrote: > > > From: Tom Lendacky > > > > > > commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24 upstream. > > > > > > There have been reports of RDRAND issues after resuming from suspend on > > > some AMD family 15h and family 16h systems. This issue stems from a BIOS > > > not performing the proper steps during resume to ensure RDRAND continues > > > to function properly. > > > > Yes. And instead of reinitializing the RDRAND on resume, this patch > > breaks support even for people with properly functioning BIOSes... > > There is no way to reinitialize RDRAND from the kernel otherwise we would > have exactly done that. If you know how to do that please tell. Would they? AMD is not exactly doing good job with communication here. If BIOS can do it, kernel can do it, too... or do you have information saying otherwise? > Also disabling it for every BIOS is the only way which can be done because > there is no way to know whether the BIOS is fixed or not at cold boot > time. And it has to be known there because applications cache the I'm pretty sure DMI-based whitelist would help here. It should be reasonably to fill it with the common machines at least. Plus, where is the CVE, and does AMD do anything to make BIOS vendors fix them? Best regards, Pavel -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany signature.asc Description: Digital signature
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Tue, 27 Aug 2019, Pavel Machek wrote: > On Tue 2019-08-27 09:50:51, Greg Kroah-Hartman wrote: > > From: Tom Lendacky > > > > commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24 upstream. > > > > There have been reports of RDRAND issues after resuming from suspend on > > some AMD family 15h and family 16h systems. This issue stems from a BIOS > > not performing the proper steps during resume to ensure RDRAND continues > > to function properly. > > Yes. And instead of reinitializing the RDRAND on resume, this patch > breaks support even for people with properly functioning BIOSes... There is no way to reinitialize RDRAND from the kernel otherwise we would have exactly done that. If you know how to do that please tell. Also disabling it for every BIOS is the only way which can be done because there is no way to know whether the BIOS is fixed or not at cold boot time. And it has to be known there because applications cache the availablity and continue using it after resume and because the valid bit is set they wont notice. There is a know to turn it back on for those who are sure that it works, but the default has to be: OFF simply because we cannot endanger everyone out there with a broken BIOS just to please you. Thanks, tglx
Re: [PATCH 4.19 72/98] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h
On Tue 2019-08-27 09:50:51, Greg Kroah-Hartman wrote:
> From: Tom Lendacky
>
> commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24 upstream.
>
> There have been reports of RDRAND issues after resuming from suspend on
> some AMD family 15h and family 16h systems. This issue stems from a BIOS
> not performing the proper steps during resume to ensure RDRAND continues
> to function properly.
Yes. And instead of reinitializing the RDRAND on resume, this patch
breaks support even for people with properly functioning BIOSes...
Also note that this is nowhere near minimum fix, and over 100 line
limit.
Best regards,
Pavel
>
> RDRAND support is indicated by CPUID Fn0001_ECX[30]. This bit can be
> reset by clearing MSR C001_1004[62]. Any software that checks for RDRAND
> support using CPUID, including the kernel, will believe that RDRAND is
> not supported.
>
> Update the CPU initialization to clear the RDRAND CPUID bit for any family
> 15h and 16h processor that supports RDRAND. If it is known that the family
> 15h or family 16h system does not have an RDRAND resume issue or that the
> system will not be placed in suspend, the "rdrand=force" kernel parameter
> can be used to stop the clearing of the RDRAND CPUID bit.
>
> Additionally, update the suspend and resume path to save and restore the
> MSR C001_1004 value to ensure that the RDRAND CPUID setting remains in
> place after resuming from suspend.
>
> Note, that clearing the RDRAND CPUID bit does not prevent a processor
> that normally supports the RDRAND instruction from executing it. So any
> code that determined the support based on family and model won't #UD.
>
> Signed-off-by: Tom Lendacky
> Signed-off-by: Borislav Petkov
> Cc: Andrew Cooper
> Cc: Andrew Morton
> Cc: Chen Yu
> Cc: "H. Peter Anvin"
> Cc: Ingo Molnar
> Cc: Jonathan Corbet
> Cc: Josh Poimboeuf
> Cc: Juergen Gross
> Cc: Kees Cook
> Cc: "linux-doc@vger.kernel.org"
> Cc: "linux...@vger.kernel.org"
> Cc: Nathan Chancellor
> Cc: Paolo Bonzini
> Cc: Pavel Machek
> Cc: "Rafael J. Wysocki"
> Cc:
> Cc: Thomas Gleixner
> Cc: "x...@kernel.org"
> Link:
> https://lkml.kernel.org/r/7543af91666f491547bd86cebb1e17c66824ab9f.1566229943.git.thomas.lenda...@amd.com
> Signed-off-by: Greg Kroah-Hartman
>
> ---
> Documentation/admin-guide/kernel-parameters.txt |7 +
> arch/x86/include/asm/msr-index.h|1
> arch/x86/kernel/cpu/amd.c | 66 ++
> arch/x86/power/cpu.c| 86
>
> 4 files changed, 147 insertions(+), 13 deletions(-)
>
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3948,6 +3948,13 @@
> Run specified binary instead of /init from the ramdisk,
> used for early userspace startup. See initrd.
>
> + rdrand= [X86]
> + force - Override the decision by the kernel to hide the
> + advertisement of RDRAND support (this affects
> + certain AMD processors because of buggy BIOS
> + support, specifically around the suspend/resume
> + path).
> +
> rdt=[HW,X86,RDT]
> Turn on/off individual RDT features. List is:
> cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
> --- a/arch/x86/include/asm/msr-index.h
> +++ b/arch/x86/include/asm/msr-index.h
> @@ -334,6 +334,7 @@
> #define MSR_AMD64_PATCH_LEVEL0x008b
> #define MSR_AMD64_TSC_RATIO 0xc104
> #define MSR_AMD64_NB_CFG 0xc001001f
> +#define MSR_AMD64_CPUID_FN_1 0xc0011004
> #define MSR_AMD64_PATCH_LOADER 0xc0010020
> #define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140
> #define MSR_AMD64_OSVW_STATUS0xc0010141
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -799,6 +799,64 @@ static void init_amd_ln(struct cpuinfo_x
> msr_set_bit(MSR_AMD64_DE_CFG, 31);
> }
>
> +static bool rdrand_force;
> +
> +static int __init rdrand_cmdline(char *str)
> +{
> + if (!str)
> + return -EINVAL;
> +
> + if (!strcmp(str, "force"))
> + rdrand_force = true;
> + else
> + return -EINVAL;
> +
> + return 0;
> +}
> +early_param("rdrand", rdrand_cmdline);
> +
> +static void clear_rdrand_cpuid_bit(struct cpuinfo_x86 *c)
> +{
> + /*
> + * Saving of the MSR used to hide the RDRAND support during
> + * suspend/resume is done by arch/x86/power/cpu.c, which is
> + * dependent on CONFIG_PM_SLEEP.
> + */
> + if (!IS_ENABLED(CONFIG_PM_SLEEP))
> + return;
> +
> + /*
> + * The nordrand option can clear X86_FEATURE_RDRAND, so check for
> + * RDRAND support using the
