On 7/1/2025 2:58 AM, Kirill A. Shutemov wrote: > From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> > > To prevent exploits for Spectre based on LAM as demonstrated by the > whitepaper [1], make LAM depend on LASS, which avoids this type of > vulnerability. > > [1] https://download.vusec.net/papers/slam_sp24.pdf > > Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > --- > arch/x86/kernel/cpu/cpuid-deps.c | 1 + > 1 file changed, 1 insertion(+) > In terms of patch ordering, wouldn't it make more sense to introduce LAM related changes after LASS has been fully enabled? This patch should probably be after Patch #16 which enables LASS. Logically, the LAM re-enabling stuff can be a separate series, but since it's only a few changed lines having it at the end seems okay. Patch 1-15 => Enable LASS Patch 16-17 => Re-enable LAM Other than that, Reviewed-by: Sohil Mehta <sohil.mehta@xxxxxxxxx> > diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c > index 98d0cdd82574..11bb9ed40140 100644 > --- a/arch/x86/kernel/cpu/cpuid-deps.c > +++ b/arch/x86/kernel/cpu/cpuid-deps.c > @@ -90,6 +90,7 @@ static const struct cpuid_dep cpuid_deps[] = { > { X86_FEATURE_FRED, X86_FEATURE_LKGS }, > { X86_FEATURE_SPEC_CTRL_SSBD, X86_FEATURE_SPEC_CTRL }, > { X86_FEATURE_LASS, X86_FEATURE_SMAP }, > + { X86_FEATURE_LAM, X86_FEATURE_LASS }, > {} > }; >
