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    SubjectRe: [PATCHv6 04/11] x86/mm: Handle LAM on context switch
    On Mon, Aug 15, 2022 at 07:17:56AM +0300, Kirill A. Shutemov wrote:
    > diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
    > index c1e31e9a85d7..fdc0b69b5da7 100644
    > --- a/arch/x86/mm/tlb.c
    > +++ b/arch/x86/mm/tlb.c
    > @@ -154,17 +154,18 @@ static inline u16 user_pcid(u16 asid)
    > return ret;
    > }
    >
    > -static inline unsigned long build_cr3(pgd_t *pgd, u16 asid)
    > +static inline unsigned long build_cr3(pgd_t *pgd, u16 asid, unsigned long lam)
    > {
    > if (static_cpu_has(X86_FEATURE_PCID)) {
    > - return __sme_pa(pgd) | kern_pcid(asid);
    > + return __sme_pa(pgd) | kern_pcid(asid) | lam;
    > } else {
    > VM_WARN_ON_ONCE(asid != 0);
    > - return __sme_pa(pgd);
    > + return __sme_pa(pgd) | lam;
    > }
    > }
    >
    > -static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
    > +static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid,
    > + unsigned long lam)
    > {
    > VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
    > /*
    > @@ -173,7 +174,7 @@ static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid)
    > * boot because all CPU's the have same capabilities:
    > */
    > VM_WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_PCID));
    > - return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH;
    > + return __sme_pa(pgd) | kern_pcid(asid) | lam | CR3_NOFLUSH;
    > }

    Looking at this; I wonder if we want something like this:

    --- a/arch/x86/mm/tlb.c
    +++ b/arch/x86/mm/tlb.c
    @@ -157,6 +157,7 @@ static inline u16 user_pcid(u16 asid)
    static inline unsigned long build_cr3(pgd_t *pgd, u16 asid, unsigned long lam)
    {
    if (static_cpu_has(X86_FEATURE_PCID)) {
    + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
    return __sme_pa(pgd) | kern_pcid(asid) | lam;
    } else {
    VM_WARN_ON_ONCE(asid != 0);
    @@ -167,14 +168,13 @@ static inline unsigned long build_cr3(pg
    static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid,
    unsigned long lam)
    {
    - VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
    /*
    * Use boot_cpu_has() instead of this_cpu_has() as this function
    * might be called during early boot. This should work even after
    * boot because all CPU's the have same capabilities:
    */
    VM_WARN_ON_ONCE(!boot_cpu_has(X86_FEATURE_PCID));
    - return __sme_pa(pgd) | kern_pcid(asid) | lam | CR3_NOFLUSH;
    + return build_cr3(pgd, asid, lam) | CR3_NOFLUSH;
    }

    /*
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