KVM: s390: Track page size in struct guest_fault

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Until now, the members of struct guest_fault are always accessed while
holding the required locks, and thus the ptep and crstep pointers can
be dereferenced safely.

There will be some new cases where callers of kvm_s390_faultin_gfn()
need to know the size of the page used to solve the fault, at which
point no locks are held anymore, and dereferencing the crstep field
is not possible.

Introduce a new crste_region3 flag for struct guest_fault to indicate
whether the crstep used to solve the fault was a region 3 entry with FC=1
(large pud).

This allows to disambiguate all three possible scenarios:
* If ptep is not NULL, the fault was solved with a pte.
* If ptep is NULL and crste_region3 is 0, a segment entry with FC=1
  (large pmd) was used.
* If ptep is NULL and crste_region3 is 1, a region 3 entry with FC=1
  (large pud) was used.

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260527144358.186359-2-imbrenda@linux.ibm.com>

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This commit is contained in:

Claudio Imbrenda 2026-05-27 16:43:54 +02:00

parent 7fd2df204f

commit 499d2e4b75

2 changed files with 3 additions and 0 deletions

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1

arch/s390/kvm/dat.h

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2

arch/s390/kvm/gmap.c

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