KVM: x86/mmu: Update iter->old_spte if cmpxchg64 on mirror SPTE "fails"

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Pass a pointer to iter->old_spte, not simply its value, when setting an
external SPTE in __tdp_mmu_set_spte_atomic(), so that the iterator's value
will be updated if the cmpxchg64 to freeze the mirror SPTE fails.  The bug
is currently benign as TDX is mutualy exclusive with all paths that do
"local" retry", e.g. clear_dirty_gfn_range() and wrprot_gfn_range().

Fixes: 77ac7079e6 ("KVM: x86/tdp_mmu: Propagate building mirror page tables")
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://patch.msgid.link/20260129011517.3545883-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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Sean Christopherson 2026-01-28 17:14:34 -08:00

parent 4487492b92

commit 02eaaffdd8

1 changed files with 5 additions and 5 deletions

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arch/x86/kvm/mmu/tdp_mmu.c

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