| Message ID | 20181206234408.1287689-2-jeremy.linton@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | add system vulnerability sysfs entries | expand |
Hi Julien, Thanks for looking at this, On 12/13/2018 03:13 AM, Julien Thierry wrote: > Hi, > > On 06/12/2018 23:44, Jeremy Linton wrote: >> From: Mian Yousaf Kaukab <ykaukab@suse.de> >> >> Add is_meltdown_safe() which is a whitelist of known safe cores. >> >> Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de> >> [Moved location of function] >> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> >> --- >> arch/arm64/kernel/cpufeature.c | 16 ++++++++++++---- >> 1 file changed, 12 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c >> index aec5ecb85737..242898395f68 100644 >> --- a/arch/arm64/kernel/cpufeature.c >> +++ b/arch/arm64/kernel/cpufeature.c >> @@ -908,8 +908,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) >> #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 >> static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ >> >> -static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, >> - int scope) >> +static bool is_cpu_meltdown_safe(void) >> { >> /* List of CPUs that are not vulnerable and don't need KPTI */ >> static const struct midr_range kpti_safe_list[] = { >> @@ -917,6 +916,16 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, >> MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), >> { /* sentinel */ } >> }; >> + /* Don't force KPTI for CPUs that are not vulnerable */ > > This is really a nit, but that comment would make more sense where > is_cpu_meltdown_safe() is called since unmap_kernel_at_el0 is the one > deciding whether to apply KPTI, is_cpu_meltdown_safe() just states > whether the core is safe of not. That is a good point, thanks. > > Otherwise: > > Reviewed-by: Julien Thierry <julien.thierry@arm.com> > > Cheers, > > Julien > >> + if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) >> + return true; >> + >> + return false; >> +} >> + >> +static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, >> + int scope) >> +{ >> char const *str = "command line option"; >> >> /* >> @@ -940,8 +949,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, >> if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) >> return true; >> >> - /* Don't force KPTI for CPUs that are not vulnerable */ >> - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) >> + if (is_cpu_meltdown_safe()) >> return false; >> >> /* Defer to CPU feature registers */ >> >
Hi, On 06/12/2018 23:44, Jeremy Linton wrote: > From: Mian Yousaf Kaukab <ykaukab@suse.de> > > Add is_meltdown_safe() which is a whitelist of known safe cores. > > Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de> > [Moved location of function] > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > --- > arch/arm64/kernel/cpufeature.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index aec5ecb85737..242898395f68 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -908,8 +908,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) > #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 > static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ > > -static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > - int scope) > +static bool is_cpu_meltdown_safe(void) > { > /* List of CPUs that are not vulnerable and don't need KPTI */ > static const struct midr_range kpti_safe_list[] = { > @@ -917,6 +916,16 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), > { /* sentinel */ } > }; > + /* Don't force KPTI for CPUs that are not vulnerable */ This is really a nit, but that comment would make more sense where is_cpu_meltdown_safe() is called since unmap_kernel_at_el0 is the one deciding whether to apply KPTI, is_cpu_meltdown_safe() just states whether the core is safe of not. Otherwise: Reviewed-by: Julien Thierry <julien.thierry@arm.com> Cheers, Julien > + if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) > + return true; > + > + return false; > +} > + > +static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > + int scope) > +{ > char const *str = "command line option"; > > /* > @@ -940,8 +949,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, > if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) > return true; > > - /* Don't force KPTI for CPUs that are not vulnerable */ > - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) > + if (is_cpu_meltdown_safe()) > return false; > > /* Defer to CPU feature registers */ > -- Julien Thierry
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index aec5ecb85737..242898395f68 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -908,8 +908,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ -static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, - int scope) +static bool is_cpu_meltdown_safe(void) { /* List of CPUs that are not vulnerable and don't need KPTI */ static const struct midr_range kpti_safe_list[] = { @@ -917,6 +916,16 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, MIDR_ALL_VERSIONS(MIDR_BRCM_VULCAN), { /* sentinel */ } }; + /* Don't force KPTI for CPUs that are not vulnerable */ + if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) + return true; + + return false; +} + +static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, + int scope) +{ char const *str = "command line option"; /* @@ -940,8 +949,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return true; - /* Don't force KPTI for CPUs that are not vulnerable */ - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) + if (is_cpu_meltdown_safe()) return false; /* Defer to CPU feature registers */