[PATCH v2 08/26] KVM: x86/mmu: Link spt to sp during allocation

David Matlack
2022-03-11T00:25:48Z

Link the shadow page table to the sp (via set_page_private()) during
allocation rather than initialization. This is a more logical place to
do it because allocation time is also where we do the reverse link
(setting sp->spt).

This creates one extra call to set_page_private(), but having multiple
calls to set_page_private() is unavoidable anyway. We either do
set_page_private() during allocation, which requires 1 per allocation
function, or we do it during initialization, which requires 1 per
initialization function.

No functional change intended.

Suggested-by: Ben Gardon <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index af60922906ef..eecb0215e636 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -274,6 +274,7 @@ static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu)

sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ set_page_private(virt_to_page(sp->spt), (unsigned long)sp);

return sp;
}
@@ -281,8 +282,6 @@ static struct kvm_mmu_page *tdp_mmu_alloc_sp(struct kvm_vcpu *vcpu)
static void tdp_mmu_init_sp(struct kvm_mmu_page *sp, tdp_ptep_t sptep,
gfn_t gfn, union kvm_mmu_page_role role)
{
- set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
-
sp->role = role;
sp->gfn = gfn;
sp->ptep = sptep;
@@ -1410,6 +1409,8 @@ static struct kvm_mmu_page *__tdp_mmu_alloc_sp_for_split(gfp_t gfp)
return NULL;
}

+ set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
+
return sp;
}

--
2.35.1.723.g4982287a31-goog