KVM: SVM: Manually recalc all MSR intercepts on userspace MSR filter change

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On a userspace MSR filter change, recalculate all MSR intercepts using the
filter-agnostic logic instead of maintaining a "shadow copy" of KVM's
desired intercepts.  The shadow bitmaps add yet another point of failure,
are confusing (e.g. what does "handled specially" mean!?!?), an eyesore,
and a maintenance burden.

Given that KVM *must* be able to recalculate the correct intercepts at any
given time, and that MSR filter updates are not hot paths, there is zero
benefit to maintaining the shadow bitmaps.

Opportunistically switch from boot_cpu_has() to cpu_feature_enabled() as
appropriate.

Link: https://lore.kernel.org/all/aCdPbZiYmtni4Bjs@google.com
Link: https://lore.kernel.org/all/20241126180253.GAZ0YNTdXH1UGeqsu6@fat_crate.local
Cc: Francesco Lavra <francescolavra.fl@gmail.com>
Link: https://lore.kernel.org/r/20250610225737.156318-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

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This commit is contained in:

Sean Christopherson 2025-06-10 15:57:24 -07:00

parent 8a056ece45

commit 160f143cc1

3 changed files with 97 additions and 280 deletions

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16

arch/x86/kvm/svm/sev.c

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359

arch/x86/kvm/svm/svm.c

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arch/x86/kvm/svm/svm.h

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