[PATCH 2/2] KVM: x86/mmu: Drop 'shared' param from tdp_mmu_link_page()

From: Sean Christopherson
Date: Tue Aug 10 2021 - 18:46:14 EST


Drop @shared from tdp_mmu_link_page() and hardcode it to work for
mmu_lock being held for read. The helper has exactly one caller and
in all likelihood will only ever have exactly one caller. Even if KVM
adds a path to install translations without an initiating page fault,
odds are very, very good that the path will just be a wrapper to the
"page fault" handler (both SNP and TDX RFCs propose patches to do
exactly that).

No functional change intended.

Cc: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index d99e064d366f..c5b901744d15 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -257,26 +257,17 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
*
* @kvm: kvm instance
* @sp: the new page
- * @shared: This operation may not be running under the exclusive use of
- * the MMU lock and the operation must synchronize with other
- * threads that might be adding or removing pages.
* @account_nx: This page replaces a NX large page and should be marked for
* eventual reclaim.
*/
static void tdp_mmu_link_page(struct kvm *kvm, struct kvm_mmu_page *sp,
- bool shared, bool account_nx)
+ bool account_nx)
{
- if (shared)
- spin_lock(&kvm->arch.tdp_mmu_pages_lock);
- else
- lockdep_assert_held_write(&kvm->mmu_lock);
-
+ spin_lock(&kvm->arch.tdp_mmu_pages_lock);
list_add(&sp->link, &kvm->arch.tdp_mmu_pages);
if (account_nx)
account_huge_nx_page(kvm, sp);
-
- if (shared)
- spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
+ spin_unlock(&kvm->arch.tdp_mmu_pages_lock);
}

/**
@@ -1062,7 +1053,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
!shadow_accessed_mask);

if (tdp_mmu_set_spte_atomic_no_dirty_log(vcpu->kvm, &iter, new_spte)) {
- tdp_mmu_link_page(vcpu->kvm, sp, true,
+ tdp_mmu_link_page(vcpu->kvm, sp,
huge_page_disallowed &&
req_level >= iter.level);

--
2.32.0.605.g8dce9f2422-goog