[PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[Laurent Dufour]

This is helpful to read the security flavor from inside the LPAR.

Export it like this in /proc/powerpc/lparcfg:

$ grep security_flavor /proc/powerpc/lparcfg
security_flavor=1

Value means:
0 Speculative execution fully enabled
1 Speculative execution controls to mitigate user-to-kernel attacks
2 Speculative execution controls to mitigate user-to-kernel and
  user-to-user side-channel attacks

Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h        | 1 +
 arch/powerpc/platforms/pseries/lparcfg.c | 2 ++
 arch/powerpc/platforms/pseries/pseries.h | 1 +
 arch/powerpc/platforms/pseries/setup.c   | 8 ++++++++
 4 files changed, 12 insertions(+)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index ed6086d57b22..455e188da26d 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -389,6 +389,7 @@
 #define H_CPU_BEHAV_FAVOUR_SECURITY	(1ull << 63) // IBM bit 0
 #define H_CPU_BEHAV_L1D_FLUSH_PR	(1ull << 62) // IBM bit 1
 #define H_CPU_BEHAV_BNDS_CHK_SPEC_BAR	(1ull << 61) // IBM bit 2
+#define H_CPU_BEHAV_FAVOUR_SECURITY_H	(1ull << 60) // IBM bit 3
 #define H_CPU_BEHAV_FLUSH_COUNT_CACHE	(1ull << 58) // IBM bit 5
 #define H_CPU_BEHAV_FLUSH_LINK_STACK	(1ull << 57) // IBM bit 6
 
diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index e278390ab28d..35f6c4929fbd 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -169,6 +169,7 @@ static void show_gpci_data(struct seq_file *m)
 	kfree(buf);
 }
 
+
 static unsigned h_pic(unsigned long *pool_idle_time,
 		      unsigned long *num_procs)
 {
@@ -537,6 +538,7 @@ static int pseries_lparcfg_data(struct seq_file *m, void *v)
 	parse_em_data(m);
 	maxmem_data(m);
 
+	seq_printf(m, "security_flavor=%u\n", pseries_security_flavor);
 	return 0;
 }
 
diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index 4fe48c04c6c2..a25517dc2515 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -111,6 +111,7 @@ static inline unsigned long cmo_get_page_size(void)
 
 int dlpar_workqueue_init(void);
 
+extern u32 pseries_security_flavor;
 void pseries_setup_security_mitigations(void);
 void pseries_lpar_read_hblkrm_characteristics(void);
 
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 46e1540abc22..59080413a269 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -85,6 +85,7 @@ EXPORT_SYMBOL(CMO_PageSize);
 
 int fwnmi_active;  /* TRUE if an FWNMI handler is present */
 int ibm_nmi_interlock_token;
+u32 pseries_security_flavor;
 
 static void pSeries_show_cpuinfo(struct seq_file *m)
 {
@@ -534,9 +535,16 @@ static void init_cpu_char_feature_flags(struct h_cpu_char_result *result)
 	/*
 	 * The features below are enabled by default, so we instead look to see
 	 * if firmware has *disabled* them, and clear them if so.
+	 * H_CPU_BEHAV_FAVOUR_SECURITY_H could be set only if
+	 * H_CPU_BEHAV_FAVOUR_SECURITY is.
 	 */
 	if (!(result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY))
 		security_ftr_clear(SEC_FTR_FAVOUR_SECURITY);
+	else if (result->behaviour & H_CPU_BEHAV_FAVOUR_SECURITY_H)
+		pseries_security_flavor = 1;
+	else
+		pseries_security_flavor = 2;
+
 
 	if (!(result->behaviour & H_CPU_BEHAV_L1D_FLUSH_PR))
 		security_ftr_clear(SEC_FTR_L1D_FLUSH_PR);
-- 
2.30.1

Re: [PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[Michael Ellerman]

Laurent Dufour <ldufour@linux.ibm.com> writes:
> This is helpful to read the security flavor from inside the LPAR.

We already have /sys/kernel/debug/powerpc/security_features.

Is that not sufficient?

> Export it like this in /proc/powerpc/lparcfg:
>
> $ grep security_flavor /proc/powerpc/lparcfg
> security_flavor=1
>
> Value means:
> 0 Speculative execution fully enabled
> 1 Speculative execution controls to mitigate user-to-kernel attacks
> 2 Speculative execution controls to mitigate user-to-kernel and
>   user-to-user side-channel attacks

Those strings come from the FSP help, but we have no guarantee it won't
mean something different in future.

cheers

Re: [PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[Laurent Dufour]

Le 05/03/2021 à 07:23, Michael Ellerman a écrit :
> Laurent Dufour <ldufour@linux.ibm.com> writes:
>> This is helpful to read the security flavor from inside the LPAR.
> 
> We already have /sys/kernel/debug/powerpc/security_features.
> 
> Is that not sufficient?

Not really, it only reports that security mitigation are on or off but not the 
level set through the ASMI menu. Furthermore, reporting it through
/proc/powerpc/lparcfg allows an easy processing by the lparstat command (see below).

> 
>> Export it like this in /proc/powerpc/lparcfg:
>>
>> $ grep security_flavor /proc/powerpc/lparcfg
>> security_flavor=1
>>
>> Value means:
>> 0 Speculative execution fully enabled
>> 1 Speculative execution controls to mitigate user-to-kernel attacks
>> 2 Speculative execution controls to mitigate user-to-kernel and
>>    user-to-user side-channel attacks
> 
> Those strings come from the FSP help, but we have no guarantee it won't
> mean something different in future.

I think this is nailed down, those strings came from:
https://www.ibm.com/support/pages/node/715841

Where it is written (regarding AIX):

On an LPAR, one can use lparstat -x to display the current mitigation mode:
0 = Speculative execution fully enabled
1 = Speculative execution controls to mitigate user-to-kernel side-channel attacks
2 = Speculative execution controls to mitigate user-to-kernel and user-to-user 
side-channel attacks

We have been requested to provide almost the same, which I proposed in 
powerpc-utils:
https://groups.google.com/g/powerpc-utils-devel/c/NaKXvdyl_UI/m/wa2stpIDAQAJ

Thanks,
Laurent.

Re: [PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[Michael Ellerman]

Laurent Dufour <ldufour@linux.ibm.com> writes:
> Le 05/03/2021 à 07:23, Michael Ellerman a écrit :
>> Laurent Dufour <ldufour@linux.ibm.com> writes:
>>> This is helpful to read the security flavor from inside the LPAR.
>> 
>> We already have /sys/kernel/debug/powerpc/security_features.
>> 
>> Is that not sufficient?
>
> Not really, it only reports that security mitigation are on or off but not the 
> level set through the ASMI menu. Furthermore, reporting it through
> /proc/powerpc/lparcfg allows an easy processing by the lparstat command (see below).
>
>> 
>>> Export it like this in /proc/powerpc/lparcfg:
>>>
>>> $ grep security_flavor /proc/powerpc/lparcfg
>>> security_flavor=1
>>>
>>> Value means:
>>> 0 Speculative execution fully enabled
>>> 1 Speculative execution controls to mitigate user-to-kernel attacks
>>> 2 Speculative execution controls to mitigate user-to-kernel and
>>>    user-to-user side-channel attacks
>> 
>> Those strings come from the FSP help, but we have no guarantee it won't
>> mean something different in future.
>
> I think this is nailed down, those strings came from:
> https://www.ibm.com/support/pages/node/715841
>
> Where it is written (regarding AIX):
>
> On an LPAR, one can use lparstat -x to display the current mitigation mode:
> 0 = Speculative execution fully enabled
> 1 = Speculative execution controls to mitigate user-to-kernel side-channel attacks
> 2 = Speculative execution controls to mitigate user-to-kernel and user-to-user 
> side-channel attacks
>
> We have been requested to provide almost the same, which I proposed in 
> powerpc-utils:
> https://groups.google.com/g/powerpc-utils-devel/c/NaKXvdyl_UI/m/wa2stpIDAQAJ

OK. Do you mind sending a v2 with all those details incorporated into
the change log?

cheers

Re: [PATCH] powerpc/pseries: export LPAR security flavor in lparcfg

[Laurent Dufour]

Le 05/03/2021 à 12:43, Michael Ellerman a écrit :
> Laurent Dufour <ldufour@linux.ibm.com> writes:
>> Le 05/03/2021 à 07:23, Michael Ellerman a écrit :
>>> Laurent Dufour <ldufour@linux.ibm.com> writes:
>>>> This is helpful to read the security flavor from inside the LPAR.
>>>
>>> We already have /sys/kernel/debug/powerpc/security_features.
>>>
>>> Is that not sufficient?
>>
>> Not really, it only reports that security mitigation are on or off but not the
>> level set through the ASMI menu. Furthermore, reporting it through
>> /proc/powerpc/lparcfg allows an easy processing by the lparstat command (see below).
>>
>>>
>>>> Export it like this in /proc/powerpc/lparcfg:
>>>>
>>>> $ grep security_flavor /proc/powerpc/lparcfg
>>>> security_flavor=1
>>>>
>>>> Value means:
>>>> 0 Speculative execution fully enabled
>>>> 1 Speculative execution controls to mitigate user-to-kernel attacks
>>>> 2 Speculative execution controls to mitigate user-to-kernel and
>>>>     user-to-user side-channel attacks
>>>
>>> Those strings come from the FSP help, but we have no guarantee it won't
>>> mean something different in future.
>>
>> I think this is nailed down, those strings came from:
>> https://www.ibm.com/support/pages/node/715841
>>
>> Where it is written (regarding AIX):
>>
>> On an LPAR, one can use lparstat -x to display the current mitigation mode:
>> 0 = Speculative execution fully enabled
>> 1 = Speculative execution controls to mitigate user-to-kernel side-channel attacks
>> 2 = Speculative execution controls to mitigate user-to-kernel and user-to-user
>> side-channel attacks
>>
>> We have been requested to provide almost the same, which I proposed in
>> powerpc-utils:
>> https://groups.google.com/g/powerpc-utils-devel/c/NaKXvdyl_UI/m/wa2stpIDAQAJ
> 
> OK. Do you mind sending a v2 with all those details incorporated into
> the change log?

Ok will do so.

Thanks