Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Alan Cox
On Fri, 26 Jan 2018 13:14:46 +0100 Yves-Alexis Perez wrote: > On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > > Some old Atoms, anything in family 5 or 4, and newer CPUs when they > > advertise > > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Alan Cox
On Fri, 26 Jan 2018 13:14:46 +0100 Yves-Alexis Perez wrote: > On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > > Some old Atoms, anything in family 5 or 4, and newer CPUs when they > > advertise > > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > >

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Arjan van de Ven
On 1/26/2018 7:27 AM, Dave Hansen wrote: On 01/26/2018 04:14 AM, Yves-Alexis Perez wrote: I know we'll still be able to manually enable PTI with a command line option, but it's also a hardening feature which has the nice side effect of emulating SMEP on CPU which don't support it (e.g the Atom

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Arjan van de Ven
On 1/26/2018 7:27 AM, Dave Hansen wrote: On 01/26/2018 04:14 AM, Yves-Alexis Perez wrote: I know we'll still be able to manually enable PTI with a command line option, but it's also a hardening feature which has the nice side effect of emulating SMEP on CPU which don't support it (e.g the Atom

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Dave Hansen
On 01/26/2018 04:14 AM, Yves-Alexis Perez wrote: > I know we'll still be able to manually enable PTI with a command line option, > but it's also a hardening feature which has the nice side effect of emulating > SMEP on CPU which don't support it (e.g the Atom boxes above). For Meltdown-vulnerable

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Dave Hansen
On 01/26/2018 04:14 AM, Yves-Alexis Perez wrote: > I know we'll still be able to manually enable PTI with a command line option, > but it's also a hardening feature which has the nice side effect of emulating > SMEP on CPU which don't support it (e.g the Atom boxes above). For Meltdown-vulnerable

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread David Woodhouse
On Fri, 2018-01-26 at 13:14 +0100, Yves-Alexis Perez wrote: > On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > > Some old Atoms, anything in family 5 or 4, and newer CPUs when they > > advertise > > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > > vulnerable.

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread David Woodhouse
On Fri, 2018-01-26 at 13:14 +0100, Yves-Alexis Perez wrote: > On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > > Some old Atoms, anything in family 5 or 4, and newer CPUs when they > > advertise > > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > > vulnerable.

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Yves-Alexis Perez
On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > vulnerable. > > Roll the AMD exemption into the x86_match_cpu() table too. > >

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-26 Thread Yves-Alexis Perez
On Wed, 2018-01-24 at 16:57 +, David Woodhouse wrote: > Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > vulnerable. > > Roll the AMD exemption into the x86_match_cpu() table too. > >

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-24 Thread Greg KH
On Wed, Jan 24, 2018 at 04:57:04PM +, David Woodhouse wrote: > Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > vulnerable. > > Roll the AMD exemption into the x86_match_cpu() table too. >

Re: [PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-24 Thread Greg KH
On Wed, Jan 24, 2018 at 04:57:04PM +, David Woodhouse wrote: > Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise > the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not > vulnerable. > > Roll the AMD exemption into the x86_match_cpu() table too. >

[PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-24 Thread David Woodhouse
Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not vulnerable. Roll the AMD exemption into the x86_match_cpu() table too. Based on suggestions from Dave Hansen and Alan Cox. Signed-off-by: David

[PATCH v3 5/6] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown

2018-01-24 Thread David Woodhouse
Some old Atoms, anything in family 5 or 4, and newer CPUs when they advertise the IA32_ARCH_CAPABILITIES MSR and it has the RDCL_NO bit set, are not vulnerable. Roll the AMD exemption into the x86_match_cpu() table too. Based on suggestions from Dave Hansen and Alan Cox. Signed-off-by: David