Re: [PATCH RFC 00/10] KVM: Enable Clang Context Analysis

[Sean Christopherson <seanjc@google.com>]

On Thu, Sep 10, 2026, Marco Elver wrote:
> Enable compiler-based static context analysis [1] for x86 KVM, along with
> prerequisite lock annotations in virt/kvm.
> 
> During the initial annotation pass, context analysis uncovered a missing
> SRCU read-side critical section in x86 PMU filter lookups; patch 1 fixes
> this bug.
> 
> The remainder of the series is strictly non-functional: it establishes
> basic function annotations, guarded_by annotations on core structs, and
> straightforward refactorings in hva/gfn range walks and guest_memfd to
> eliminate conditional locking patterns that cannot be tracked statically.
> 
> Annotating the MMU (mmu/mmu.c, mmu/tdp_mmu.c), i8259, and Xen requires
> more invasive changes and is deferred to follow-ups.
> 
> [1] https://docs.kernel.org/next/dev-tools/context-analysis.html

...

>  43 files changed, 745 insertions(+), 236 deletions(-)

For me, there needs to be a _lot_ more explanation of what this buys us to justify
the extra annotations and ongoing maintenance burden.  And to a lesser extent, why
we should rework code to play nice with context analysis (I assume we can simply
opt-out on a per-function basis if we don't want to play nice?).

I'd also like to see what the MMU changes look like before committing to supporting
this.