lkml.org 
[lkml]   [2020]   [Sep]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 07/22] kvm: mmu: Support zapping SPTEs in the TDP MMU
From
Date
On 30/09/20 08:15, Sean Christopherson wrote:
>> kvm_zap_obsolete_pages(kvm);
>> +
>> + if (kvm->arch.tdp_mmu_enabled)
>> + kvm_tdp_mmu_zap_all(kvm);
>
> Haven't looked into how this works; is kvm_tdp_mmu_zap_all() additive to
> what is done by the legacy zapping, or is it a replacement?

It's additive because the shadow MMU is still used for nesting.

>> +
>> spin_unlock(&kvm->mmu_lock);
>> }
>> @@ -57,8 +58,13 @@ bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa)
>> return root->tdp_mmu_page;
>> }
>>
>> +static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
>> + gfn_t start, gfn_t end);
>> +
>> static void free_tdp_mmu_root(struct kvm *kvm, struct kvm_mmu_page *root)
>> {
>> + gfn_t max_gfn = 1ULL << (boot_cpu_data.x86_phys_bits - PAGE_SHIFT);
>
> BIT_ULL(...)

Not sure about that. Here the point is not to have a single bit, but to
do a power of two. Same for the version below.

>> + * If the MMU lock is contended or this thread needs to yield, flushes
>> + * the TLBs, releases, the MMU lock, yields, reacquires the MMU lock,
>> + * restarts the tdp_iter's walk from the root, and returns true.
>> + * If no yield is needed, returns false.
>> + */
>> +static bool tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter)
>> +{
>> + if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
>> + kvm_flush_remote_tlbs(kvm);
>> + cond_resched_lock(&kvm->mmu_lock);
>> + tdp_iter_refresh_walk(iter);
>> + return true;
>> + } else {
>> + return false;
>> + }
>
> Kernel style is to not bother with an "else" if the "if" returns.

I have rewritten all of this in my version anyway. :)

Paolo

\
 
 \ /
  Last update: 2020-09-30 08:29    [W:0.081 / U:2.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site