Re: [PATCH v2 0/2] KVM: TDX: INIT_MEM_REGION fixes

[Sean Christopherson <seanjc@google.com>]

On Tue, Sep 22, 2026, Ackerley Tng wrote:
> Sean Christopherson <seanjc@google.com> writes:
> 
> > I completely lost track of this, meant to post these patches weeks ago.
> > Compile tested only.
> >
> > v2:
> >  - Fix an off-by-one bug.
> >  - Use gpa_t instead of raw u64.
> >  - Tweak the order of checks to bundle similar checks together, and to perform
> >    the super basic checks (alignment, size, etc.) first.
> >
> > v1: https://lore.kernel.org/all/ak0skG064rhKUC8d@google.com
> >
> > Haotian Jiang (1):
> >   KVM: TDX: Reject INIT_MEM_REGION if number of bytes would overflow a
> >     u64
> >
> > Sean Christopherson (1):
> >   KVM: TDX: Fix a benign off-by-one bug on the end GPA for
> >     INIT_MEM_REGION
> >
> >  arch/x86/kvm/vmx/tdx.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> >
> > base-commit: a806d364ef288a6443a1337820ea8410a7ccc6b3
> > --
> > 2.55.0.679.g6767b8d81c-goog
> 
> Looks good to me, just a question on the use of check_*_overflow: I
> thought Sean didn't like burying an out-param in an if-statement? [1]

I don't, but in this case I found it to be the lesser evil.  I think it helps
that both the out-params are used only in the same if-statement.  One could argue
that's even *more* evil, but t doesn't "surprise" me as much, e.g. I'm not having
to hunt for where some variable in the main loop is set.

> [1] https://lore.kernel.org/all/ag8BmtzxTlcuA_zy@google.com