Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-16 Thread George Dunlap
On 01/16/2018 07:12 AM, Jan Beulich wrote: On 15.01.18 at 17:54, wrote: >> On Jan 12, 2018, at 05:19, Jan Beulich wrote: >>> >>> This is a very simplistic change limiting the amount of memory a running >>> 64-bit PV guest has mapped (and hence available

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-15 Thread Rich Persaud
On Jan 12, 2018, at 05:19, Jan Beulich wrote: > > This is a very simplistic change limiting the amount of memory a running > 64-bit PV guest has mapped (and hence available for attacking): Only the > mappings of stack, IDT, and TSS are being cloned from the direct map > into

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-15 Thread Jan Beulich
>>> On 13.01.18 at 18:48, wrote: > On 12/01/18 10:19, Jan Beulich wrote: >> This is a very simplistic change limiting the amount of memory a running >> 64-bit PV guest has mapped (and hence available for attacking): Only the >> mappings of stack, IDT, and TSS are being

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-13 Thread Andrew Cooper
On 12/01/18 10:19, Jan Beulich wrote: > This is a very simplistic change limiting the amount of memory a running > 64-bit PV guest has mapped (and hence available for attacking): Only the > mappings of stack, IDT, and TSS are being cloned from the direct map > into per-CPU page tables. Guest

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread Stefano Stabellini
On Fri, 12 Jan 2018, Jan Beulich wrote: > >>> On 12.01.18 at 18:02, wrote: > > On Fri, Jan 12, 2018 at 03:19:38AM -0700, Jan Beulich wrote: > >> @@ -799,6 +982,10 @@ void __init smp_prepare_cpus(unsigned in > >> > >> stack_base[0] = stack_start; > >> > >> +if (

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread Jan Beulich
>>> On 12.01.18 at 18:02, wrote: > On Fri, Jan 12, 2018 at 03:19:38AM -0700, Jan Beulich wrote: >> @@ -799,6 +982,10 @@ void __init smp_prepare_cpus(unsigned in >> >> stack_base[0] = stack_start; >> >> +if ( !setup_cpu_root_pgt(0) ) >> +panic("No memory

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread Roger Pau Monné
On Fri, Jan 12, 2018 at 03:19:38AM -0700, Jan Beulich wrote: > This is a very simplistic change limiting the amount of memory a running > 64-bit PV guest has mapped (and hence available for attacking): Only the > mappings of stack, IDT, and TSS are being cloned from the direct map > into per-CPU

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread Jan Beulich
>>> On 12.01.18 at 11:19, wrote: > @@ -727,6 +907,9 @@ static int cpu_smpboot_alloc(unsigned in > set_ist(_tables[cpu][TRAP_nmi], IST_NONE); > set_ist(_tables[cpu][TRAP_machine_check], IST_NONE); > > +if ( !setup_cpu_root_pgt(cpu) ) > +goto

Re: [Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread George Dunlap
On Fri, Jan 12, 2018 at 10:19 AM, Jan Beulich wrote: > This is a very simplistic change limiting the amount of memory a running > 64-bit PV guest has mapped (and hence available for attacking): Only the > mappings of stack, IDT, and TSS are being cloned from the direct map >

[Xen-devel] [PATCH] x86: Meltdown band-aid against malicious 64-bit PV guests

2018-01-12 Thread Jan Beulich
This is a very simplistic change limiting the amount of memory a running 64-bit PV guest has mapped (and hence available for attacking): Only the mappings of stack, IDT, and TSS are being cloned from the direct map into per-CPU page tables. Guest controlled parts of the page tables are being