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KVM: s390: vsie: Check alignment of BSCA header

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The VSIE code currently checks that the BSCA struct fits within
a page, and returns a validity exception 0x003b if it doesn't.
The BSCA is pinned in memory rather than shadowed (see block
comment at end of kvm_s390_cpu_feat_init()), so enforcing the
CPU entries to be on the same pinned page makes sense.

Except those entries aren't going to be used below the guest,
and according to the definition of that validity exception only
the header of the BSCA (everything but the CPU entries) needs to
be within a page. Adjust the alignment check to account for that.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
This commit is contained in:
Eric Farman
2025-11-07 03:49:27 +01:00
committed by Janosch Frank
parent 8e8678e740
commit 44acac00be
1 changed files with 1 additions and 1 deletions
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2
arch/s390/kvm/vsie.c
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@@ -782,7 +782,7 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
else if ((gpa & ~0x1fffUL) == kvm_s390_get_prefix(vcpu))
rc = set_validity_icpt(scb_s, 0x0011U);
else if ((gpa & PAGE_MASK) !=
((gpa + sizeof(struct bsca_block) - 1) & PAGE_MASK))
((gpa + offsetof(struct bsca_block, cpu[0]) - 1) & PAGE_MASK))
rc = set_validity_icpt(scb_s, 0x003bU);
if (!rc) {
rc = pin_guest_page(vcpu->kvm, gpa, &hpa);