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Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste

From Heiko Carstens <heiko.carstens@de.ibm.com>
Newsgroups linux.kernel
Subject Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste
Date 2017-06-02 12:30 +0200
Message-ID <tNS09-8e7-5@gated-at.bofh.it> (permalink)
References <tMvS2-2uZ-7@gated-at.bofh.it> <tNvPY-1sb-15@gated-at.bofh.it> <tNOSC-698-9@gated-at.bofh.it> <tNRns-7G9-27@gated-at.bofh.it>
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On Fri, Jun 02, 2017 at 11:46:47AM +0200, Martin Schwidefsky wrote:
> On Fri, 2 Jun 2017 09:02:10 +0200
> Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> > Maybe this is a bit over-simplified, but might work.
> This is not over-simplified at all, that does work:

Good!

> +struct arch_elf_state {
> +};
> +
> +#define INIT_ARCH_ELF_STATE { }
> +
> +#define arch_elf_pt_proc(ehdr, phdr, elf, interp, state) (0)
> +#define arch_check_elf(ehdr, interp, interp_ehdr, state)	\
> +({								\
> +	struct elf64_hdr *hdr = (void*) ehdr;			\
> +	int _rc = 0;						\
> +	if (hdr->e_ident[EI_CLASS] == ELFCLASS64 &&		\
> +	    (hdr->e_flags & 0x00000002) &&			\
> +	    !page_table_allocate_pgste &&			\
> +	    !current->mm->context.alloc_pgste) {		\
> +		current->mm->context.alloc_pgste = 1;		\

However, I think this is over-simplified, unless I'm mistaken.

If you set current->mm->context.alloc_pgste here, then that means that 4k
page tables will be freed when the original mm will be released, instead of
the correct 2k ones.

I think you need an additional intermediate context flag here. Something
like current->mm->context.request_pgste or whatever, no?

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[PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste David Hildenbrand <david@redhat.com> - 2017-05-29 18:40 +0200
  [PATCH RFC 2/2] KVM: s390: Introduce KVM_VM_S390_LATE_MMAP David Hildenbrand <david@redhat.com> - 2017-05-29 18:40 +0200
  [PATCH RFC 1/2] s390x: mm: allow mixed page table types (2k and 4k) David Hildenbrand <david@redhat.com> - 2017-05-29 18:40 +0200
    Re: [PATCH RFC 1/2] s390x: mm: allow mixed page table types (2k and  4k) Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-01 13:40 +0200
      Re: [PATCH RFC 1/2] s390x: mm: allow mixed page table types (2k and  4k) David Hildenbrand <david@redhat.com> - 2017-06-01 14:50 +0200
    Re: [PATCH RFC 1/2] s390x: mm: allow mixed page table types (2k and  4k) David Hildenbrand <david@redhat.com> - 2017-06-01 15:00 +0200
      Re: [PATCH RFC 1/2] s390x: mm: allow mixed page table types (2k and  4k) Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 09:20 +0200
  Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-01 12:50 +0200
    Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-01 13:30 +0200
    Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste David Hildenbrand <david@redhat.com> - 2017-06-01 13:30 +0200
      Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Heiko Carstens <heiko.carstens@de.ibm.com> - 2017-06-02 09:10 +0200
    Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Heiko Carstens <heiko.carstens@de.ibm.com> - 2017-06-02 09:10 +0200
      Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-02 09:20 +0200
        Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 09:30 +0200
          Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-02 10:20 +0200
        Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 09:30 +0200
      Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 09:20 +0200
      Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-02 11:50 +0200
        Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 12:20 +0200
          Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-02 13:00 +0200
            Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Christian Borntraeger <borntraeger@de.ibm.com> - 2017-06-02 15:30 +0200
              Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-07 14:40 +0200
        Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste Heiko Carstens <heiko.carstens@de.ibm.com> - 2017-06-02 12:30 +0200
          Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable  vm.alloc_pgste Martin Schwidefsky <schwidefsky@de.ibm.com> - 2017-06-02 12:50 +0200
      Re: [PATCH RFC 0/2] KVM: s390: avoid having to enable vm.alloc_pgste David Hildenbrand <david@redhat.com> - 2017-06-02 13:00 +0200

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