| Message ID | 20190417175815.16905-7-julien.grall@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | xen/arm: TLB flush helpers rework | expand |
On 17.04.19 20:58, Julien Grall wrote: > All the TLBs helpers invalidate all the TLB entries are using the same > pattern: > DSB SY > TLBI ... > DSB SY > ISB > > This pattern is following pattern recommended by the Arm Arm to ensure > visibility of updates to translation tables (see K10-5610 in ARM DDI > 0487.A.k). I can't find 0487.A.k, only aj [1], next one is b. I guess you are referring `Ensuring the visibility of updates to translation tables for a multiprocessor`? [1] https://developer.arm.com/docs/ddi0487/aj > > We have been a bit too eager in Xen and use system-wide DSBs when this > can be limited to the inner-shareable domain. > > Furthermore, the first DSB can be restrict further to only store in the > inner-shareable domain. This is because the DSB is here to ensure > visibility of the update to translation table walks. > > Lastly, there are a lack of documentation in most of the TLBs helper. > > Rather than trying to update the helpers one by one, this patch > introduce a per-arch macro to generate the TLB helpers. This will be > easier to update the TLBs helper in the future and the documentation. > > Signed-off-by: Julien Grall <julien.grall@arm.com> > --- > xen/include/asm-arm/arm32/flushtlb.h | 73 ++++++++++++++-------------------- > xen/include/asm-arm/arm64/flushtlb.h | 76 +++++++++++++++--------------------- > 2 files changed, 60 insertions(+), 89 deletions(-) > > diff --git a/xen/include/asm-arm/arm32/flushtlb.h b/xen/include/asm-arm/arm32/flushtlb.h > index b629db61cb..9085e65011 100644 > --- a/xen/include/asm-arm/arm32/flushtlb.h > +++ b/xen/include/asm-arm/arm32/flushtlb.h > @@ -1,59 +1,44 @@ > #ifndef __ASM_ARM_ARM32_FLUSHTLB_H__ > #define __ASM_ARM_ARM32_FLUSHTLB_H__ > > -/* Flush local TLBs, current VMID only */ > -static inline void flush_guest_tlb_local(void) > -{ > - dsb(sy); > - > - WRITE_CP32((uint32_t) 0, TLBIALL); > - > - dsb(sy); > - isb(); > +/* > + * Every invalidation operation use the following patterns: > + * > + * DSB ISHST // Ensure prior page-tables updates have completed > + * TLBI... // Invalidate the TLB > + * DSB ISH // Ensure the TLB invalidation has completed > + * ISB // See explanation below > + * > + * For Xen page-tables the ISB will discard any instructions fetched > + * from the old mappings. > + * > + * For the Stage-2 page-tables the ISB ensures the completion of the DSB > + * (and therefore the TLB invalidation) before continuing. So we know > + * the TLBs cannot contain an entry for a mapping we may have removed. > + */ > +#define TLB_HELPER(name, tlbop) \ > +static inline void name(void) \ > +{ \ > + dsb(ishst); \ > + WRITE_CP32(0, tlbop); \ > + dsb(ish); \ > + isb(); \ > } > > -/* Flush inner shareable TLBs, current VMID only */ > -static inline void flush_guest_tlb(void) > -{ > - dsb(sy); > - > - WRITE_CP32((uint32_t) 0, TLBIALLIS); > +/* Flush local TLBs, current VMID only */ > +TLB_HELPER(flush_guest_tlb_local, TLBIALL); > > - dsb(sy); > - isb(); > -} > +/* Flush inner shareable TLBs, current VMID only */ > +TLB_HELPER(flush_guest_tlb, TLBIALLIS); > > /* Flush local TLBs, all VMIDs, non-hypervisor mode */ > -static inline void flush_all_guests_tlb_local(void) > -{ > - dsb(sy); > - > - WRITE_CP32((uint32_t) 0, TLBIALLNSNH); > - > - dsb(sy); > - isb(); > -} > +TLB_HELPER(flush_all_guests_tlb_local, TLBIALLNSNH); > > /* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */ > -static inline void flush_all_guests_tlb(void) > -{ > - dsb(sy); > - > - WRITE_CP32((uint32_t) 0, TLBIALLNSNHIS); > - > - dsb(sy); > - isb(); > -} > +TLB_HELPER(flush_all_guests_tlb, TLBIALLNSNHIS); > > /* Flush all hypervisor mappings from the TLB of the local processor. */ > -static inline void flush_xen_tlb_local(void) > -{ > - asm volatile("dsb;" /* Ensure preceding are visible */ > - CMD_CP32(TLBIALLH) > - "dsb;" /* Ensure completion of the TLB flush */ > - "isb;" > - : : : "memory"); > -} > +TLB_HELPER(flush_xen_tlb_local, TLBIALLH); > > /* Flush TLB of local processor for address va. */ > static inline void __flush_xen_tlb_one_local(vaddr_t va) > diff --git a/xen/include/asm-arm/arm64/flushtlb.h b/xen/include/asm-arm/arm64/flushtlb.h > index 2fed34b2ec..ceec59542e 100644 > --- a/xen/include/asm-arm/arm64/flushtlb.h > +++ b/xen/include/asm-arm/arm64/flushtlb.h > @@ -1,60 +1,46 @@ > #ifndef __ASM_ARM_ARM64_FLUSHTLB_H__ > #define __ASM_ARM_ARM64_FLUSHTLB_H__ > > -/* Flush local TLBs, current VMID only */ > -static inline void flush_guest_tlb_local(void) > -{ > - asm volatile( > - "dsb sy;" > - "tlbi vmalls12e1;" > - "dsb sy;" > - "isb;" > - : : : "memory"); > +/* > + * Every invalidation operation use the following patterns: > + * > + * DSB ISHST // Ensure prior page-tables updates have completed > + * TLBI... // Invalidate the TLB > + * DSB ISH // Ensure the TLB invalidation has completed > + * ISB // See explanation below > + * > + * For Xen page-tables the ISB will discard any instructions fetched > + * from the old mappings. > + * > + * For the Stage-2 page-tables the ISB ensures the completion of the DSB > + * (and therefore the TLB invalidation) before continuing. So we know > + * the TLBs cannot contain an entry for a mapping we may have removed. > + */ > +#define TLB_HELPER(name, tlbop) \ > +static inline void name(void) \ > +{ \ > + asm volatile( \ > + "dsb ishst;" \ > + "tlbi " # tlbop ";" \ > + "dsb ish;" \ > + "isb;" \ > + : : : "memory"); \ > } > > +/* Flush local TLBs, current VMID only. */ > +TLB_HELPER(flush_guest_tlb_local, vmalls12e1); > + > /* Flush innershareable TLBs, current VMID only */ > -static inline void flush_guest_tlb(void) > -{ > - asm volatile( > - "dsb sy;" > - "tlbi vmalls12e1is;" > - "dsb sy;" > - "isb;" > - : : : "memory"); > -} > +TLB_HELPER(flush_guest_tlb, vmalls12e1is); > > /* Flush local TLBs, all VMIDs, non-hypervisor mode */ > -static inline void flush_all_guests_tlb_local(void) > -{ > - asm volatile( > - "dsb sy;" > - "tlbi alle1;" > - "dsb sy;" > - "isb;" > - : : : "memory"); > -} > +TLB_HELPER(flush_all_guests_tlb_local, alle1); > > /* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */ > -static inline void flush_all_guests_tlb(void) > -{ > - asm volatile( > - "dsb sy;" > - "tlbi alle1is;" > - "dsb sy;" > - "isb;" > - : : : "memory"); > -} > +TLB_HELPER(flush_all_guests_tlb, alle1is); > > /* Flush all hypervisor mappings from the TLB of the local processor. */ > -static inline void flush_xen_tlb_local(void) > -{ > - asm volatile ( > - "dsb sy;" /* Ensure visibility of PTE writes */ > - "tlbi alle2;" /* Flush hypervisor TLB */ > - "dsb sy;" /* Ensure completion of TLB flush */ > - "isb;" > - : : : "memory"); > -} > +TLB_HELPER(flush_xen_tlb_local, alle2); > > /* Flush TLB of local processor for address va. */ > static inline void __flush_xen_tlb_one_local(vaddr_t va) > With minor notes, Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
On 25/04/2019 19:01, Andrii Anisov wrote: > > > On 17.04.19 20:58, Julien Grall wrote: >> All the TLBs helpers invalidate all the TLB entries are using the same >> pattern: >> DSB SY >> TLBI ... >> DSB SY >> ISB >> >> This pattern is following pattern recommended by the Arm Arm to ensure >> visibility of updates to translation tables (see K10-5610 in ARM DDI >> 0487.A.k). > > I can't find 0487.A.k, only aj [1], next one is b. > I guess you are referring `Ensuring the visibility of updates to > translation tables for a multiprocessor`? Oh, I vaguely remember a version of the Arm Arm been re-issued because of the mistakes during the release. This might well have been A.k. I am not sure why I use A.k because this is a pretty old spec. I should have used the last one (i.e D.a). Anyway, I am indeed referring to `Ensuring the visibility of updates to translation tables for a multiprocessor`. I will update the commit message. [...] > > With minor notes, > > Reviewed-by: Andrii Anisov <andrii_anisov@epam.com> Thank you! Cheers, -- Julien Grall
On 25.04.19 23:42, Julien Grall wrote: > I am not sure why I use A.k because this is a pretty old spec. I did mean that A.k. is not publicly available, even now, so it is not quite right to refer such a document, at least without mentioning it is internal. > I should > have used the last one (i.e D.a). > Anyway, I am indeed referring to `Ensuring the visibility of updates to > translation tables for a multiprocessor`. I will update the commit message. Cool.
Hi, On 26/04/2019 14:49, Andrii Anisov wrote: > > > On 25.04.19 23:42, Julien Grall wrote: >> I am not sure why I use A.k because this is a pretty old spec. > I did mean that A.k. is not publicly available, even now, so it is not quite > right to refer such a document, at least without mentioning it is internal Please avoid to take my words out of context... As you read the sentence above, you probably noticed that A.k was published with defects in it and probably the reasons why it can't be found today. I download all my specs from public website to avoid potential disclosure of internal content. If you look at Google, the spec was actually public at some point (see [1] for instance). In what you quote, I merely pointed out that I should not have used it because it is pretty old (~2 and half years). Cheers, [1] https://lkml.org/lkml/2017/3/3/247
On 26.04.19 17:06, Julien Grall wrote: > Hi, > > On 26/04/2019 14:49, Andrii Anisov wrote: >> >> >> On 25.04.19 23:42, Julien Grall wrote: >>> I am not sure why I use A.k because this is a pretty old spec. >> I did mean that A.k. is not publicly available, even now, so it is not quite right to refer such a document, at least without mentioning it is internal > Please avoid to take my words out of context... As you read the sentence above, you probably noticed that A.k was published with defects in it and probably the reasons why it can't be found today. > > I download all my specs from public website to avoid potential disclosure of internal content. If you look at Google, the spec was actually public at some point (see [1] for instance). I understand that. But now, at this patch publication and review moment, the A.k. document is not available. And is a bit confusing. > In what you quote, I merely pointed out that I should not have used it because it is pretty old (~2 and half years). Referring the most up-to-date document is alway a good choice.
diff --git a/xen/include/asm-arm/arm32/flushtlb.h b/xen/include/asm-arm/arm32/flushtlb.h index b629db61cb..9085e65011 100644 --- a/xen/include/asm-arm/arm32/flushtlb.h +++ b/xen/include/asm-arm/arm32/flushtlb.h @@ -1,59 +1,44 @@ #ifndef __ASM_ARM_ARM32_FLUSHTLB_H__ #define __ASM_ARM_ARM32_FLUSHTLB_H__ -/* Flush local TLBs, current VMID only */ -static inline void flush_guest_tlb_local(void) -{ - dsb(sy); - - WRITE_CP32((uint32_t) 0, TLBIALL); - - dsb(sy); - isb(); +/* + * Every invalidation operation use the following patterns: + * + * DSB ISHST // Ensure prior page-tables updates have completed + * TLBI... // Invalidate the TLB + * DSB ISH // Ensure the TLB invalidation has completed + * ISB // See explanation below + * + * For Xen page-tables the ISB will discard any instructions fetched + * from the old mappings. + * + * For the Stage-2 page-tables the ISB ensures the completion of the DSB + * (and therefore the TLB invalidation) before continuing. So we know + * the TLBs cannot contain an entry for a mapping we may have removed. + */ +#define TLB_HELPER(name, tlbop) \ +static inline void name(void) \ +{ \ + dsb(ishst); \ + WRITE_CP32(0, tlbop); \ + dsb(ish); \ + isb(); \ } -/* Flush inner shareable TLBs, current VMID only */ -static inline void flush_guest_tlb(void) -{ - dsb(sy); - - WRITE_CP32((uint32_t) 0, TLBIALLIS); +/* Flush local TLBs, current VMID only */ +TLB_HELPER(flush_guest_tlb_local, TLBIALL); - dsb(sy); - isb(); -} +/* Flush inner shareable TLBs, current VMID only */ +TLB_HELPER(flush_guest_tlb, TLBIALLIS); /* Flush local TLBs, all VMIDs, non-hypervisor mode */ -static inline void flush_all_guests_tlb_local(void) -{ - dsb(sy); - - WRITE_CP32((uint32_t) 0, TLBIALLNSNH); - - dsb(sy); - isb(); -} +TLB_HELPER(flush_all_guests_tlb_local, TLBIALLNSNH); /* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */ -static inline void flush_all_guests_tlb(void) -{ - dsb(sy); - - WRITE_CP32((uint32_t) 0, TLBIALLNSNHIS); - - dsb(sy); - isb(); -} +TLB_HELPER(flush_all_guests_tlb, TLBIALLNSNHIS); /* Flush all hypervisor mappings from the TLB of the local processor. */ -static inline void flush_xen_tlb_local(void) -{ - asm volatile("dsb;" /* Ensure preceding are visible */ - CMD_CP32(TLBIALLH) - "dsb;" /* Ensure completion of the TLB flush */ - "isb;" - : : : "memory"); -} +TLB_HELPER(flush_xen_tlb_local, TLBIALLH); /* Flush TLB of local processor for address va. */ static inline void __flush_xen_tlb_one_local(vaddr_t va) diff --git a/xen/include/asm-arm/arm64/flushtlb.h b/xen/include/asm-arm/arm64/flushtlb.h index 2fed34b2ec..ceec59542e 100644 --- a/xen/include/asm-arm/arm64/flushtlb.h +++ b/xen/include/asm-arm/arm64/flushtlb.h @@ -1,60 +1,46 @@ #ifndef __ASM_ARM_ARM64_FLUSHTLB_H__ #define __ASM_ARM_ARM64_FLUSHTLB_H__ -/* Flush local TLBs, current VMID only */ -static inline void flush_guest_tlb_local(void) -{ - asm volatile( - "dsb sy;" - "tlbi vmalls12e1;" - "dsb sy;" - "isb;" - : : : "memory"); +/* + * Every invalidation operation use the following patterns: + * + * DSB ISHST // Ensure prior page-tables updates have completed + * TLBI... // Invalidate the TLB + * DSB ISH // Ensure the TLB invalidation has completed + * ISB // See explanation below + * + * For Xen page-tables the ISB will discard any instructions fetched + * from the old mappings. + * + * For the Stage-2 page-tables the ISB ensures the completion of the DSB + * (and therefore the TLB invalidation) before continuing. So we know + * the TLBs cannot contain an entry for a mapping we may have removed. + */ +#define TLB_HELPER(name, tlbop) \ +static inline void name(void) \ +{ \ + asm volatile( \ + "dsb ishst;" \ + "tlbi " # tlbop ";" \ + "dsb ish;" \ + "isb;" \ + : : : "memory"); \ } +/* Flush local TLBs, current VMID only. */ +TLB_HELPER(flush_guest_tlb_local, vmalls12e1); + /* Flush innershareable TLBs, current VMID only */ -static inline void flush_guest_tlb(void) -{ - asm volatile( - "dsb sy;" - "tlbi vmalls12e1is;" - "dsb sy;" - "isb;" - : : : "memory"); -} +TLB_HELPER(flush_guest_tlb, vmalls12e1is); /* Flush local TLBs, all VMIDs, non-hypervisor mode */ -static inline void flush_all_guests_tlb_local(void) -{ - asm volatile( - "dsb sy;" - "tlbi alle1;" - "dsb sy;" - "isb;" - : : : "memory"); -} +TLB_HELPER(flush_all_guests_tlb_local, alle1); /* Flush innershareable TLBs, all VMIDs, non-hypervisor mode */ -static inline void flush_all_guests_tlb(void) -{ - asm volatile( - "dsb sy;" - "tlbi alle1is;" - "dsb sy;" - "isb;" - : : : "memory"); -} +TLB_HELPER(flush_all_guests_tlb, alle1is); /* Flush all hypervisor mappings from the TLB of the local processor. */ -static inline void flush_xen_tlb_local(void) -{ - asm volatile ( - "dsb sy;" /* Ensure visibility of PTE writes */ - "tlbi alle2;" /* Flush hypervisor TLB */ - "dsb sy;" /* Ensure completion of TLB flush */ - "isb;" - : : : "memory"); -} +TLB_HELPER(flush_xen_tlb_local, alle2); /* Flush TLB of local processor for address va. */ static inline void __flush_xen_tlb_one_local(vaddr_t va)
All the TLBs helpers invalidate all the TLB entries are using the same pattern: DSB SY TLBI ... DSB SY ISB This pattern is following pattern recommended by the Arm Arm to ensure visibility of updates to translation tables (see K10-5610 in ARM DDI 0487.A.k). We have been a bit too eager in Xen and use system-wide DSBs when this can be limited to the inner-shareable domain. Furthermore, the first DSB can be restrict further to only store in the inner-shareable domain. This is because the DSB is here to ensure visibility of the update to translation table walks. Lastly, there are a lack of documentation in most of the TLBs helper. Rather than trying to update the helpers one by one, this patch introduce a per-arch macro to generate the TLB helpers. This will be easier to update the TLBs helper in the future and the documentation. Signed-off-by: Julien Grall <julien.grall@arm.com> --- xen/include/asm-arm/arm32/flushtlb.h | 73 ++++++++++++++-------------------- xen/include/asm-arm/arm64/flushtlb.h | 76 +++++++++++++++--------------------- 2 files changed, 60 insertions(+), 89 deletions(-)