Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi, This does not seem to have subsumed the AMD specific code in x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown Commit a8799fd14d9f7f385a5a5c86cde247caf4bb0320 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.9.81=a8799fd14d9f7f385a5a5c86cde247caf4bb0320 x86/kaiser: Check boottime cmdline params Commit 8018307a45a90ab2eecfd03d48b7efb31707df37 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/arch/x86/mm/kaiser.c?h=v4.9.75=8018307a45a90ab2eecfd03d48b7efb31707df37 Here, we can see: +skip: + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + goto disable; Refer to 4.9.81's kaiser.c https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.9.81 Also 4.4.115's kaiser.c https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.4.115 Cheers, Nick
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi Arjan and Greg, Sorry if I am not being clear enough. My point is that there is a check for X86_VENDOR_AMD now in two places. It is still hardcoded for the auto boot option which I think should not be there. The patch on that basis looked incomplete to me. Put another way, there is no effect to the auto option where the contents of cpu_no_meltdown[] are changed and cpu_vulnerable_to_meltdown returns differently. The auto option does not make use of a determination of the X86_BUG_CPU_MELTDOWN state. This seems wrong to me. It does not seem correct to me for the auto option to have this duplication with a check for just X86_VENDOR_AMD. Regards, Nick
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi, This should use boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN)) - I am preparing patches. Best, Nick
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi I do not have a tested patch, but I expect the change would be something like: skip: - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + if (!static_cpu_has_bug(X86_BUG_CPU_MELTDOWN)) goto disable; Cheers, Nick On Tue, Feb 13, 2018 at 4:32 PM, Greg Kroah-Hartman <gre...@linuxfoundation.org> wrote: > On Tue, Feb 13, 2018 at 03:27:47PM +0000, Nick Lowe wrote: >> Hi Arjan and Greg, >> >> Sorry if I am not being clear enough. >> >> My point is that there is a check for X86_VENDOR_AMD now in two places. >> >> It is still hardcoded for the auto boot option which I think should >> not be there. The patch on that basis looked incomplete to me. >> >> Put another way, there is no effect to the auto option where the >> contents of cpu_no_meltdown[] are changed and >> cpu_vulnerable_to_meltdown returns differently. >> >> The auto option does not make use of a determination of the >> X86_BUG_CPU_MELTDOWN state. >> >> This seems wrong to me. It does not seem correct to me for the auto >> option to have this duplication with a check for just X86_VENDOR_AMD. > > Do you have a patch that reflects what you want to see changed here? > > And can you test it? :) > > I don't have any AMD hardware, sorry. > > thanks, > > greg k-h
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi, This does not seem to have subsumed the AMD specific code in x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown Commit a8799fd14d9f7f385a5a5c86cde247caf4bb0320 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=v4.9.81=a8799fd14d9f7f385a5a5c86cde247caf4bb0320 x86/kaiser: Check boottime cmdline params Commit 8018307a45a90ab2eecfd03d48b7efb31707df37 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/arch/x86/mm/kaiser.c?h=v4.9.75=8018307a45a90ab2eecfd03d48b7efb31707df37 Here, we can see: +skip: + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + goto disable; Refer to 4.9.81's kaiser.c https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.9.81 Also 4.4.115's kaiser.c https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/arch/x86/mm/kaiser.c?h=v4.4.115 Cheers, Nick
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi Arjan and Greg, Sorry if I am not being clear enough. My point is that there is a check for X86_VENDOR_AMD now in two places. It is still hardcoded for the auto boot option which I think should not be there. The patch on that basis looked incomplete to me. Put another way, there is no effect to the auto option where the contents of cpu_no_meltdown[] are changed and cpu_vulnerable_to_meltdown returns differently. The auto option does not make use of a determination of the X86_BUG_CPU_MELTDOWN state. This seems wrong to me. It does not seem correct to me for the auto option to have this duplication with a check for just X86_VENDOR_AMD. Regards, Nick
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi I do not have a tested patch, but I expect the change would be something like: skip: - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + if (!static_cpu_has_bug(X86_BUG_CPU_MELTDOWN)) goto disable; Cheers, Nick On Tue, Feb 13, 2018 at 4:32 PM, Greg Kroah-Hartman wrote: > On Tue, Feb 13, 2018 at 03:27:47PM +0000, Nick Lowe wrote: >> Hi Arjan and Greg, >> >> Sorry if I am not being clear enough. >> >> My point is that there is a check for X86_VENDOR_AMD now in two places. >> >> It is still hardcoded for the auto boot option which I think should >> not be there. The patch on that basis looked incomplete to me. >> >> Put another way, there is no effect to the auto option where the >> contents of cpu_no_meltdown[] are changed and >> cpu_vulnerable_to_meltdown returns differently. >> >> The auto option does not make use of a determination of the >> X86_BUG_CPU_MELTDOWN state. >> >> This seems wrong to me. It does not seem correct to me for the auto >> option to have this duplication with a check for just X86_VENDOR_AMD. > > Do you have a patch that reflects what you want to see changed here? > > And can you test it? :) > > I don't have any AMD hardware, sorry. > > thanks, > > greg k-h
Re: [PATCH 4.9 43/92] x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
Hi, This should use boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN)) - I am preparing patches. Best, Nick
