diff mbox

arm64: Work around Falkor erratum 1009

Message ID 20161207200431.4587-1-cov@codeaurora.org (mailing list archive)
State New, archived
Headers show

Commit Message

Christopher Covington Dec. 7, 2016, 8:04 p.m. UTC 
From: Shanker Donthineni <shankerd@codeaurora.org>

During a TLB invalidate sequence targeting the inner shareable
domain, Falkor may prematurely complete the DSB before all loads
and stores using the old translation are observed; instruction
fetches are not subject to the conditions of this erratum.

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Christopher Covington <cov@codeaurora.org>
---
 arch/arm64/Kconfig                | 10 +++++++++
 arch/arm64/include/asm/cpucaps.h  |  3 ++-
 arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/cpu_errata.c    |  7 +++++++
 arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
 5 files changed, 96 insertions(+), 6 deletions(-)

Comments

Will Deacon Dec. 8, 2016, 11:20 a.m. UTC | #1 
On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:
> From: Shanker Donthineni <shankerd@codeaurora.org>
> 
> During a TLB invalidate sequence targeting the inner shareable
> domain, Falkor may prematurely complete the DSB before all loads
> and stores using the old translation are observed; instruction
> fetches are not subject to the conditions of this erratum.
> 
> Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
> Signed-off-by: Christopher Covington <cov@codeaurora.org>
> ---
>  arch/arm64/Kconfig                | 10 +++++++++
>  arch/arm64/include/asm/cpucaps.h  |  3 ++-
>  arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/cpu_errata.c    |  7 +++++++
>  arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
>  5 files changed, 96 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 1004a3d..125440f 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -485,6 +485,16 @@ config QCOM_FALKOR_ERRATUM_E1003
>  
>  	  If unsure, say Y.
>  
> +config QCOM_FALKOR_ERRATUM_E1009
> +	bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
> +	default y
> +	help
> +	  Falkor CPU may prematurely complete a DSB following a TLBI xxIS
> +	  invalidate maintenance operations. Repeat the TLBI operation one
> +	  more time to fix the issue.
> +
> +	  If unsure, say Y.

Call me perverse, but I like this workaround. People often tend to screw
up TLBI and DVM sync, but the IPI-based workaround is horribly invasive
and fragile. Simply repeating the operation tends to be enough to make
the chance of failure small enough to be acceptable.

> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
> index cb6a8c2..5357d7f 100644
> --- a/arch/arm64/include/asm/cpucaps.h
> +++ b/arch/arm64/include/asm/cpucaps.h
> @@ -35,7 +35,8 @@
>  #define ARM64_HYP_OFFSET_LOW			14
>  #define ARM64_MISMATCHED_CACHE_LINE_SIZE	15
>  #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	16
> +#define ARM64_WORKAROUND_QCOM_FALKOR_E1009	17

Could you rename this to something like ARM64_WORKAROUND_REPEAT_TLBI, so
that it could potentially be used by others?

>  
> -#define ARM64_NCAPS				17
> +#define ARM64_NCAPS				18
>  
>  #endif /* __ASM_CPUCAPS_H */
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index deab523..03bafc5 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -23,6 +23,7 @@
>  
>  #include <linux/sched.h>
>  #include <asm/cputype.h>
> +#include <asm/alternative.h>
>  
>  /*
>   * Raw TLBI operations.
> @@ -94,6 +95,13 @@ static inline void flush_tlb_all(void)
>  	dsb(ishst);
>  	__tlbi(vmalle1is);
>  	dsb(ish);
> +	asm volatile(ALTERNATIVE(
> +		     "nop \n"
> +		     "nop \n",
> +		     "tlbi vmalle1is \n"
> +		     "dsb ish \n",
> +		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
> +		     : :);

I'd much rather this was part of the __tlbi macro, which would hopefully
restrict this to one place in the code.

Will
Marc Zyngier Dec. 8, 2016, 11:35 a.m. UTC | #2 
On 08/12/16 11:20, Will Deacon wrote:
> On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:
>> From: Shanker Donthineni <shankerd@codeaurora.org>
>>
>> During a TLB invalidate sequence targeting the inner shareable
>> domain, Falkor may prematurely complete the DSB before all loads
>> and stores using the old translation are observed; instruction
>> fetches are not subject to the conditions of this erratum.
>>
>> Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
>> Signed-off-by: Christopher Covington <cov@codeaurora.org>
>> ---
>>  arch/arm64/Kconfig                | 10 +++++++++
>>  arch/arm64/include/asm/cpucaps.h  |  3 ++-
>>  arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
>>  arch/arm64/kernel/cpu_errata.c    |  7 +++++++
>>  arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
>>  5 files changed, 96 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 1004a3d..125440f 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -485,6 +485,16 @@ config QCOM_FALKOR_ERRATUM_E1003
>>  
>>  	  If unsure, say Y.
>>  
>> +config QCOM_FALKOR_ERRATUM_E1009
>> +	bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
>> +	default y
>> +	help
>> +	  Falkor CPU may prematurely complete a DSB following a TLBI xxIS
>> +	  invalidate maintenance operations. Repeat the TLBI operation one
>> +	  more time to fix the issue.
>> +
>> +	  If unsure, say Y.
> 
> Call me perverse, but I like this workaround. People often tend to screw
> up TLBI and DVM sync, but the IPI-based workaround is horribly invasive
> and fragile. Simply repeating the operation tends to be enough to make
> the chance of failure small enough to be acceptable.
> 
>> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
>> index cb6a8c2..5357d7f 100644
>> --- a/arch/arm64/include/asm/cpucaps.h
>> +++ b/arch/arm64/include/asm/cpucaps.h
>> @@ -35,7 +35,8 @@
>>  #define ARM64_HYP_OFFSET_LOW			14
>>  #define ARM64_MISMATCHED_CACHE_LINE_SIZE	15
>>  #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	16
>> +#define ARM64_WORKAROUND_QCOM_FALKOR_E1009	17
> 
> Could you rename this to something like ARM64_WORKAROUND_REPEAT_TLBI, so
> that it could potentially be used by others?

And add a parameter to it so that we can generate multiple TLBIs,
depending on the level of brokenness? ;-)

	M.
Mark Rutland Dec. 8, 2016, 11:45 a.m. UTC | #3 
On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:
> From: Shanker Donthineni <shankerd@codeaurora.org>
> 
> During a TLB invalidate sequence targeting the inner shareable
> domain, Falkor may prematurely complete the DSB before all loads
> and stores using the old translation are observed; instruction
> fetches are not subject to the conditions of this erratum.
> 
> Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
> Signed-off-by: Christopher Covington <cov@codeaurora.org>
> ---
>  arch/arm64/Kconfig                | 10 +++++++++
>  arch/arm64/include/asm/cpucaps.h  |  3 ++-
>  arch/arm64/include/asm/tlbflush.h | 43 +++++++++++++++++++++++++++++++++++++++
>  arch/arm64/kernel/cpu_errata.c    |  7 +++++++
>  arch/arm64/kvm/hyp/tlb.c          | 39 ++++++++++++++++++++++++++++++-----
>  5 files changed, 96 insertions(+), 6 deletions(-)

Please update Documentation/arm64/silicon-errata.txt respectively.

[...]

>  #include <linux/sched.h>
>  #include <asm/cputype.h>
> +#include <asm/alternative.h>

Nit: please keep includes (alphabetically) ordered (at least below the
linux/ or asm/ level).

[...]

> +	asm volatile(ALTERNATIVE(
> +		     "nop \n"
> +		     "nop \n",
> +		     "tlbi vmalle1is \n"
> +		     "dsb ish \n",

As a general note, perhaps we want a C compatible NOP_ALTERNATIVE() so
that the nop case can be implicitly generated for sequences like this.

Thanks,
Mark.
Catalin Marinas Dec. 8, 2016, 1:27 p.m. UTC | #4 
On Thu, Dec 08, 2016 at 11:45:12AM +0000, Mark Rutland wrote:
> On Wed, Dec 07, 2016 at 03:04:31PM -0500, Christopher Covington wrote:
> > +	asm volatile(ALTERNATIVE(
> > +		     "nop \n"
> > +		     "nop \n",
> > +		     "tlbi vmalle1is \n"
> > +		     "dsb ish \n",
> 
> As a general note, perhaps we want a C compatible NOP_ALTERNATIVE() so
> that the nop case can be implicitly generated for sequences like this.

It's also worth checking what cpus_have_const_cap() would generate for
the default (no workaround required) case.
diff mbox

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 1004a3d..125440f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -485,6 +485,16 @@  config QCOM_FALKOR_ERRATUM_E1003
 
 	  If unsure, say Y.
 
+config QCOM_FALKOR_ERRATUM_E1009
+	bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
+	default y
+	help
+	  Falkor CPU may prematurely complete a DSB following a TLBI xxIS
+	  invalidate maintenance operations. Repeat the TLBI operation one
+	  more time to fix the issue.
+
+	  If unsure, say Y.
+
 endmenu
 
 
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index cb6a8c2..5357d7f 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -35,7 +35,8 @@ 
 #define ARM64_HYP_OFFSET_LOW			14
 #define ARM64_MISMATCHED_CACHE_LINE_SIZE	15
 #define ARM64_WORKAROUND_QCOM_FALKOR_E1003	16
+#define ARM64_WORKAROUND_QCOM_FALKOR_E1009	17
 
-#define ARM64_NCAPS				17
+#define ARM64_NCAPS				18
 
 #endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index deab523..03bafc5 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -23,6 +23,7 @@ 
 
 #include <linux/sched.h>
 #include <asm/cputype.h>
+#include <asm/alternative.h>
 
 /*
  * Raw TLBI operations.
@@ -94,6 +95,13 @@  static inline void flush_tlb_all(void)
 	dsb(ishst);
 	__tlbi(vmalle1is);
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi vmalle1is \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : :);
 	isb();
 }
 
@@ -104,6 +112,13 @@  static inline void flush_tlb_mm(struct mm_struct *mm)
 	dsb(ishst);
 	__tlbi(aside1is, asid);
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi aside1is, %0 \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (asid));
 }
 
 static inline void flush_tlb_page(struct vm_area_struct *vma,
@@ -114,6 +129,13 @@  static inline void flush_tlb_page(struct vm_area_struct *vma,
 	dsb(ishst);
 	__tlbi(vale1is, addr);
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi vale1is, %0 \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (addr));
 }
 
 /*
@@ -145,6 +167,13 @@  static inline void __flush_tlb_range(struct vm_area_struct *vma,
 			__tlbi(vae1is, addr);
 	}
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi vae1is, %0 \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (end));
 }
 
 static inline void flush_tlb_range(struct vm_area_struct *vma,
@@ -169,6 +198,13 @@  static inline void flush_tlb_kernel_range(unsigned long start, unsigned long end
 	for (addr = start; addr < end; addr += 1 << (PAGE_SHIFT - 12))
 		__tlbi(vaae1is, addr);
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi vaae1is, %0 \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (end));
 	isb();
 }
 
@@ -183,6 +219,13 @@  static inline void __flush_tlb_pgtable(struct mm_struct *mm,
 
 	__tlbi(vae1is, addr);
 	dsb(ish);
+	asm volatile(ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "tlbi vae1is, %0 \n"
+		     "dsb ish \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (addr));
 }
 
 #endif
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 3789e2f..8013579 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -137,6 +137,13 @@  const struct arm64_cpu_capabilities arm64_errata[] = {
 		MIDR_RANGE(MIDR_QCOM_FALKOR_V1, 0x00, 0x00),
 	},
 #endif
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1009
+	{
+		.desc = "Qualcomm Falkor erratum E1009",
+		.capability = ARM64_WORKAROUND_QCOM_FALKOR_E1009,
+		MIDR_RANGE(MIDR_QCOM_FALKOR_V1, 0x00, 0x00),
+	},
+#endif
 	{
 	}
 };
diff --git a/arch/arm64/kvm/hyp/tlb.c b/arch/arm64/kvm/hyp/tlb.c
index 88e2f2b..dfd3a77 100644
--- a/arch/arm64/kvm/hyp/tlb.c
+++ b/arch/arm64/kvm/hyp/tlb.c
@@ -16,6 +16,7 @@ 
  */
 
 #include <asm/kvm_hyp.h>
+#include <asm/alternative.h>
 
 void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 {
@@ -32,7 +33,14 @@  void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 	 * whole of Stage-1. Weep...
 	 */
 	ipa >>= 12;
-	asm volatile("tlbi ipas2e1is, %0" : : "r" (ipa));
+	asm volatile("tlbi ipas2e1is, %0 \n"
+		     ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "dsb ish \n"
+		     "tlbi ipas2e1is, %0 \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : "r" (ipa));
 
 	/*
 	 * We have to ensure completion of the invalidation at Stage-2,
@@ -41,7 +49,14 @@  void __hyp_text __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa)
 	 * the Stage-1 invalidation happened first.
 	 */
 	dsb(ish);
-	asm volatile("tlbi vmalle1is" : : );
+	asm volatile("tlbi vmalle1is \n"
+		     ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "dsb ish \n"
+		     "tlbi vmalle1is \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : );
 	dsb(ish);
 	isb();
 
@@ -57,7 +72,14 @@  void __hyp_text __kvm_tlb_flush_vmid(struct kvm *kvm)
 	write_sysreg(kvm->arch.vttbr, vttbr_el2);
 	isb();
 
-	asm volatile("tlbi vmalls12e1is" : : );
+	asm volatile("tlbi vmalls12e1is \n"
+		     ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "dsb ish \n"
+		     "tlbi vmalls12e1is \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     : : );
 	dsb(ish);
 	isb();
 
@@ -82,7 +104,14 @@  void __hyp_text __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu)
 void __hyp_text __kvm_flush_vm_context(void)
 {
 	dsb(ishst);
-	asm volatile("tlbi alle1is	\n"
-		     "ic ialluis	  ": : );
+	asm volatile("tlbi alle1is \n"
+		     ALTERNATIVE(
+		     "nop \n"
+		     "nop \n",
+		     "dsb ish \n"
+		     "tlbi alle1is \n",
+		     ARM64_WORKAROUND_QCOM_FALKOR_E1009)
+		     "ic ialluis \n"
+		     : : );
 	dsb(ish);
 }