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Add a knob for disabling/enabling HTT, "machdep.hyperthreading_allowed".

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Default off due to information disclosure on multi-user systems.

Submitted by:	cperciva
Reviewed by:	jhb
This commit is contained in:
Jacques Vidrine 2005-05-13 00:10:56 +00:00
parent a6761eb377
commit f6108b6158
4 changed files with 218 additions and 0 deletions
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101
sys/amd64/amd64/mp_machdep.c
View File

@ -142,6 +142,9 @@ static int start_ap(int apic_id);
static void release_aps(void *dummy);
static int hlt_logical_cpus;
static u_int hyperthreading_cpus;
static cpumask_t hyperthreading_cpus_mask;
static int hyperthreading_allowed;
static struct sysctl_ctx_list logical_cpu_clist;
static u_int bootMP_size;
@ -301,6 +304,7 @@ void
cpu_mp_start(void)
{
int i;
u_int threads_per_cache, p[4];
/* Initialize the logical ID to APIC ID table. */
for (i = 0; i < MAXCPU; i++) {
@ -340,6 +344,48 @@ cpu_mp_start(void)
if (cpu_feature & CPUID_HTT)
logical_cpus = (cpu_procinfo & CPUID_HTT_CORES) >> 16;
/*
* Work out if hyperthreading is *really* enabled. This
* is made really ugly by the fact that processors lie: Dual
* core processors claim to be hyperthreaded even when they're
* not, presumably because they want to be treated the same
* way as HTT with respect to per-cpu software licensing.
* At the time of writing (May 12, 2005) the only hyperthreaded
* cpus are from Intel, and Intel's dual-core processors can be
* identified via the "deterministic cache parameters" cpuid
* calls.
*/
/*
* First determine if this is an Intel processor which claims
* to have hyperthreading support.
*/
if ((cpu_feature & CPUID_HTT) &&
(strcmp(cpu_vendor, "GenuineIntel") == 0)) {
/*
* If the "deterministic cache parameters" cpuid calls
* are available, use them.
*/
if (cpu_high >= 4) {
/* Ask the processor about up to 32 caches. */
for (i = 0; i < 32; i++) {
cpuid_count(4, i, p);
threads_per_cache = ((p[0] & 0x3ffc000) >> 14) + 1;
if (hyperthreading_cpus < threads_per_cache)
hyperthreading_cpus = threads_per_cache;
if ((p[0] & 0x1f) == 0)
break;
}
}
/*
* If the deterministic cache parameters are not
* available, or if no caches were reported to exist,
* just accept what the HTT flag indicated.
*/
if (hyperthreading_cpus == 0)
hyperthreading_cpus = logical_cpus;
}
set_logical_apic_ids();
}
@ -478,6 +524,11 @@ init_secondary(void)
if (logical_cpus > 1 && PCPU_GET(apic_id) % logical_cpus != 0)
logical_cpus_mask |= PCPU_GET(cpumask);
/* Determine if we are a hyperthread. */
if (hyperthreading_cpus > 1 &&
PCPU_GET(apic_id) % hyperthreading_cpus != 0)
hyperthreading_cpus_mask |= PCPU_GET(cpumask);
/* Build our map of 'other' CPUs. */
PCPU_SET(other_cpus, all_cpus & ~PCPU_GET(cpumask));
@ -1081,6 +1132,9 @@ sysctl_hlt_cpus(SYSCTL_HANDLER_ARGS)
else
hlt_logical_cpus = 0;
if (! hyperthreading_allowed)
mask |= hyperthreading_cpus_mask;
if ((mask & all_cpus) == all_cpus)
mask &= ~(1<<0);
hlt_cpus_mask = mask;
@ -1105,6 +1159,9 @@ sysctl_hlt_logical_cpus(SYSCTL_HANDLER_ARGS)
else
hlt_cpus_mask &= ~logical_cpus_mask;
if (! hyperthreading_allowed)
hlt_cpus_mask |= hyperthreading_cpus_mask;
if ((hlt_cpus_mask & all_cpus) == all_cpus)
hlt_cpus_mask &= ~(1<<0);
@ -1112,6 +1169,34 @@ sysctl_hlt_logical_cpus(SYSCTL_HANDLER_ARGS)
return (error);
}
static int
sysctl_hyperthreading_allowed(SYSCTL_HANDLER_ARGS)
{
int allowed, error;
allowed = hyperthreading_allowed;
error = sysctl_handle_int(oidp, &allowed, 0, req);
if (error || !req->newptr)
return (error);
if (allowed)
hlt_cpus_mask &= ~hyperthreading_cpus_mask;
else
hlt_cpus_mask |= hyperthreading_cpus_mask;
if (logical_cpus_mask != 0 &&
(hlt_cpus_mask & logical_cpus_mask) == logical_cpus_mask)
hlt_logical_cpus = 1;
else
hlt_logical_cpus = 0;
if ((hlt_cpus_mask & all_cpus) == all_cpus)
hlt_cpus_mask &= ~(1<<0);
hyperthreading_allowed = allowed;
return (error);
}
static void
cpu_hlt_setup(void *dummy __unused)
{
@ -1131,6 +1216,22 @@ cpu_hlt_setup(void *dummy __unused)
if (hlt_logical_cpus)
hlt_cpus_mask |= logical_cpus_mask;
/*
* If necessary for security purposes, force
* hyperthreading off, regardless of the value
* of hlt_logical_cpus.
*/
if (hyperthreading_cpus_mask) {
TUNABLE_INT_FETCH("machdep.hyperthreading_allowed",
&hyperthreading_allowed);
SYSCTL_ADD_PROC(&logical_cpu_clist,
SYSCTL_STATIC_CHILDREN(_machdep), OID_AUTO,
"hyperthreading_allowed", CTLTYPE_INT|CTLFLAG_RW,
0, 0, sysctl_hyperthreading_allowed, "IU", "");
if (! hyperthreading_allowed)
hlt_cpus_mask |= hyperthreading_cpus_mask;
}
}
}
SYSINIT(cpu_hlt, SI_SUB_SMP, SI_ORDER_ANY, cpu_hlt_setup, NULL);

8
sys/amd64/include/cpufunc.h
View File

@ -113,6 +113,14 @@ do_cpuid(u_int ax, u_int *p)
: "0" (ax));
}
static __inline void
cpuid_count(u_int ax, u_int cx, u_int *p)
{
__asm __volatile("cpuid"
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax), "c" (cx));
}
static __inline void
enable_intr(void)
{

101
sys/i386/i386/mp_machdep.c
View File

@ -214,6 +214,9 @@ static int start_ap(int apic_id);
static void release_aps(void *dummy);
static int hlt_logical_cpus;
static u_int hyperthreading_cpus;
static cpumask_t hyperthreading_cpus_mask;
static int hyperthreading_allowed;
static struct sysctl_ctx_list logical_cpu_clist;
static void
@ -350,6 +353,7 @@ void
cpu_mp_start(void)
{
int i;
u_int threads_per_cache, p[4];
POSTCODE(MP_START_POST);
@ -401,6 +405,48 @@ cpu_mp_start(void)
if (cpu_feature & CPUID_HTT)
logical_cpus = (cpu_procinfo & CPUID_HTT_CORES) >> 16;
/*
* Work out if hyperthreading is *really* enabled. This
* is made really ugly by the fact that processors lie: Dual
* core processors claim to be hyperthreaded even when they're
* not, presumably because they want to be treated the same
* way as HTT with respect to per-cpu software licensing.
* At the time of writing (May 12, 2005) the only hyperthreaded
* cpus are from Intel, and Intel's dual-core processors can be
* identified via the "deterministic cache parameters" cpuid
* calls.
*/
/*
* First determine if this is an Intel processor which claims
* to have hyperthreading support.
*/
if ((cpu_feature & CPUID_HTT) &&
(strcmp(cpu_vendor, "GenuineIntel") == 0)) {
/*
* If the "deterministic cache parameters" cpuid calls
* are available, use them.
*/
if (cpu_high >= 4) {
/* Ask the processor about up to 32 caches. */
for (i = 0; i < 32; i++) {
cpuid_count(4, i, p);
threads_per_cache = ((p[0] & 0x3ffc000) >> 14) + 1;
if (hyperthreading_cpus < threads_per_cache)
hyperthreading_cpus = threads_per_cache;
if ((p[0] & 0x1f) == 0)
break;
}
}
/*
* If the deterministic cache parameters are not
* available, or if no caches were reported to exist,
* just accept what the HTT flag indicated.
*/
if (hyperthreading_cpus == 0)
hyperthreading_cpus = logical_cpus;
}
set_logical_apic_ids();
}
@ -542,6 +588,11 @@ init_secondary(void)
if (logical_cpus > 1 && PCPU_GET(apic_id) % logical_cpus != 0)
logical_cpus_mask |= PCPU_GET(cpumask);
/* Determine if we are a hyperthread. */
if (hyperthreading_cpus > 1 &&
PCPU_GET(apic_id) % hyperthreading_cpus != 0)
hyperthreading_cpus_mask |= PCPU_GET(cpumask);
/* Build our map of 'other' CPUs. */
PCPU_SET(other_cpus, all_cpus & ~PCPU_GET(cpumask));
@ -1300,6 +1351,9 @@ sysctl_hlt_cpus(SYSCTL_HANDLER_ARGS)
else
hlt_logical_cpus = 0;
if (! hyperthreading_allowed)
mask |= hyperthreading_cpus_mask;
if ((mask & all_cpus) == all_cpus)
mask &= ~(1<<0);
hlt_cpus_mask = mask;
@ -1324,6 +1378,9 @@ sysctl_hlt_logical_cpus(SYSCTL_HANDLER_ARGS)
else
hlt_cpus_mask &= ~logical_cpus_mask;
if (! hyperthreading_allowed)
hlt_cpus_mask |= hyperthreading_cpus_mask;
if ((hlt_cpus_mask & all_cpus) == all_cpus)
hlt_cpus_mask &= ~(1<<0);
@ -1331,6 +1388,34 @@ sysctl_hlt_logical_cpus(SYSCTL_HANDLER_ARGS)
return (error);
}
static int
sysctl_hyperthreading_allowed(SYSCTL_HANDLER_ARGS)
{
int allowed, error;
allowed = hyperthreading_allowed;
error = sysctl_handle_int(oidp, &allowed, 0, req);
if (error || !req->newptr)
return (error);
if (allowed)
hlt_cpus_mask &= ~hyperthreading_cpus_mask;
else
hlt_cpus_mask |= hyperthreading_cpus_mask;
if (logical_cpus_mask != 0 &&
(hlt_cpus_mask & logical_cpus_mask) == logical_cpus_mask)
hlt_logical_cpus = 1;
else
hlt_logical_cpus = 0;
if ((hlt_cpus_mask & all_cpus) == all_cpus)
hlt_cpus_mask &= ~(1<<0);
hyperthreading_allowed = allowed;
return (error);
}
static void
cpu_hlt_setup(void *dummy __unused)
{
@ -1350,6 +1435,22 @@ cpu_hlt_setup(void *dummy __unused)
if (hlt_logical_cpus)
hlt_cpus_mask |= logical_cpus_mask;
/*
* If necessary for security purposes, force
* hyperthreading off, regardless of the value
* of hlt_logical_cpus.
*/
if (hyperthreading_cpus_mask) {
TUNABLE_INT_FETCH("machdep.hyperthreading_allowed",
&hyperthreading_allowed);
SYSCTL_ADD_PROC(&logical_cpu_clist,
SYSCTL_STATIC_CHILDREN(_machdep), OID_AUTO,
"hyperthreading_allowed", CTLTYPE_INT|CTLFLAG_RW,
0, 0, sysctl_hyperthreading_allowed, "IU", "");
if (! hyperthreading_allowed)
hlt_cpus_mask |= hyperthreading_cpus_mask;
}
}
}
SYSINIT(cpu_hlt, SI_SUB_SMP, SI_ORDER_ANY, cpu_hlt_setup, NULL);

8
sys/i386/include/cpufunc.h
View File

@ -92,6 +92,14 @@ do_cpuid(u_int ax, u_int *p)
: "0" (ax));
}
static __inline void
cpuid_count(u_int ax, u_int cx, u_int *p)
{
__asm __volatile("cpuid"
: "=a" (p[0]), "=b" (p[1]), "=c" (p[2]), "=d" (p[3])
: "0" (ax), "c" (cx));
}
static __inline void
enable_intr(void)
{