Messages in this thread | | | Subject | Re: [patch 05/15] x86/tlb: Move __flush_tlb() out of line | From | Jürgen Groß <> | Date | Mon, 20 Apr 2020 16:38:17 +0200 |
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On 20.04.20 16:26, Tom Lendacky wrote: > On 4/20/20 9:03 AM, Jürgen Groß wrote: >> On 20.04.20 15:48, Tom Lendacky wrote: >>> On 4/19/20 3:31 PM, Thomas Gleixner wrote: >>>> cpu_tlbstate is exported because various TLB related functions need >>>> access >>>> to it, but cpu_tlbstate is sensitive information which should only be >>>> accessed by well contained kernel functions and not be directly >>>> exposed to >>>> modules. >>>> >>>> The various TLB flush functions need access to cpu_tlbstate. As a first >>>> step move __flush_tlb() out of line and hide the native function. The >>>> latter can be static when CONFIG_PARAVIRT is disabled. >>>> >>>> Consolidate the name space while at it and remove the pointless extra >>>> wrapper in the paravirt code. >>>> >>>> No functional change. >>>> >>>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> >>>> Cc: Thomas Lendacky <Thomas.Lendacky@amd.com> >>>> Cc: Juergen Gross <jgross@suse.com> >>>> --- >>>> arch/x86/include/asm/paravirt.h | 4 +++- >>>> arch/x86/include/asm/tlbflush.h | 29 >>>> +++++------------------------ >>>> arch/x86/kernel/cpu/mtrr/generic.c | 4 ++-- >>>> arch/x86/kernel/paravirt.c | 7 +------ >>>> arch/x86/mm/mem_encrypt.c | 2 +- >>>> arch/x86/mm/tlb.c | 33 >>>> ++++++++++++++++++++++++++++++++- >>>> arch/x86/platform/uv/tlb_uv.c | 2 +- >>>> 7 files changed, 45 insertions(+), 36 deletions(-) >>>> >>>> --- a/arch/x86/include/asm/paravirt.h >>>> +++ b/arch/x86/include/asm/paravirt.h >>>> @@ -47,7 +47,9 @@ static inline void slow_down_io(void) >>>> #endif >>>> } >>>> -static inline void __flush_tlb(void) >>>> +void native_flush_tlb_local(void); >>>> + >>>> +static inline void __flush_tlb_local(void) >>>> { >>>> PVOP_VCALL0(mmu.flush_tlb_user); >>>> } >>>> --- a/arch/x86/include/asm/tlbflush.h >>>> +++ b/arch/x86/include/asm/tlbflush.h >>>> @@ -140,12 +140,13 @@ static inline unsigned long build_cr3_no >>>> return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH; >>>> } >>>> +void flush_tlb_local(void); >>>> + >>>> #ifdef CONFIG_PARAVIRT >>>> #include <asm/paravirt.h> >>>> #else >>>> -#define __flush_tlb() __native_flush_tlb() >>>> -#define __flush_tlb_global() __native_flush_tlb_global() >>>> -#define __flush_tlb_one_user(addr) __native_flush_tlb_one_user(addr) >>>> +#define __flush_tlb_global() __native_flush_tlb_global() >>>> +#define __flush_tlb_one_user(addr) >>>> __native_flush_tlb_one_user(addr) >>>> #endif >>>> struct tlb_context { >>>> @@ -371,24 +372,6 @@ static inline void invalidate_user_asid( >>>> } >>>> /* >>>> - * flush the entire current user mapping >>>> - */ >>>> -static inline void __native_flush_tlb(void) >>>> -{ >>>> - /* >>>> - * Preemption or interrupts must be disabled to protect the access >>>> - * to the per CPU variable and to prevent being preempted between >>>> - * read_cr3() and write_cr3(). >>>> - */ >>>> - WARN_ON_ONCE(preemptible()); >>>> - >>>> - invalidate_user_asid(this_cpu_read(cpu_tlbstate.loaded_mm_asid)); >>>> - >>>> - /* If current->mm == NULL then the read_cr3() "borrows" an mm */ >>>> - native_write_cr3(__native_read_cr3()); >>>> -} >>>> - >>>> -/* >>>> * flush everything >>>> */ >>>> static inline void __native_flush_tlb_global(void) >>>> @@ -461,7 +444,7 @@ static inline void __flush_tlb_all(void) >>>> /* >>>> * !PGE -> !PCID (setup_pcid()), thus every flush is total. >>>> */ >>>> - __flush_tlb(); >>>> + flush_tlb_local(); >>>> } >>>> } >>>> @@ -537,8 +520,6 @@ struct flush_tlb_info { >>>> bool freed_tables; >>>> }; >>>> -#define local_flush_tlb() __flush_tlb() >>>> - >>>> #define flush_tlb_mm(mm) \ >>>> flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true) >>>> --- a/arch/x86/kernel/cpu/mtrr/generic.c >>>> +++ b/arch/x86/kernel/cpu/mtrr/generic.c >>>> @@ -761,7 +761,7 @@ static void prepare_set(void) __acquires >>>> /* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */ >>>> count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); >>>> - __flush_tlb(); >>>> + flush_tlb_local(); >>>> /* Save MTRR state */ >>>> rdmsr(MSR_MTRRdefType, deftype_lo, deftype_hi); >>>> @@ -778,7 +778,7 @@ static void post_set(void) __releases(se >>>> { >>>> /* Flush TLBs (no need to flush caches - they are disabled) */ >>>> count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL); >>>> - __flush_tlb(); >>>> + flush_tlb_local(); >>>> /* Intel (P6) standard MTRRs */ >>>> mtrr_wrmsr(MSR_MTRRdefType, deftype_lo, deftype_hi); >>>> --- a/arch/x86/kernel/paravirt.c >>>> +++ b/arch/x86/kernel/paravirt.c >>>> @@ -160,11 +160,6 @@ unsigned paravirt_patch_insns(void *insn >>>> return insn_len; >>>> } >>>> -static void native_flush_tlb(void) >>>> -{ >>>> - __native_flush_tlb(); >>>> -} >>>> - >>>> /* >>>> * Global pages have to be flushed a bit differently. Not a real >>>> * performance problem because this does not happen often. >>>> @@ -359,7 +354,7 @@ struct paravirt_patch_template pv_ops = >>>> #endif /* CONFIG_PARAVIRT_XXL */ >>>> /* Mmu ops. */ >>>> - .mmu.flush_tlb_user = native_flush_tlb, >>>> + .mmu.flush_tlb_user = native_flush_tlb_local, >>>> .mmu.flush_tlb_kernel = native_flush_tlb_global, >>>> .mmu.flush_tlb_one_user = native_flush_tlb_one_user, >>>> .mmu.flush_tlb_others = native_flush_tlb_others, >>>> --- a/arch/x86/mm/mem_encrypt.c >>>> +++ b/arch/x86/mm/mem_encrypt.c >>>> @@ -134,7 +134,7 @@ static void __init __sme_early_map_unmap >>>> size = (size <= PMD_SIZE) ? 0 : size - PMD_SIZE; >>>> } while (size); >>>> - __native_flush_tlb(); >>>> + flush_tlb_local(); >>> >>> This invoked __native_flush_tlb() because of how early it is called >>> and the paravirt ops support isn't set up yet, resulting in a crash >>> if not invoking the native version directly. So this needs a "native" >>> version of the tlb flush to invoke. >> >> I don't think this is still true. With my rework of pvops to have all >> functions in one struct which is initialized statically initially >> everything should work from the time the kernel is mapped. >> >> In case it doesn't there is something very wrong IMO. > > The memory encryption support was implemented in 4.14, so it's quite > possible that this isn't an issue now. I'll test out the patch and > verify it. What release did your pvops rework land in?
4.20.
Juergen
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