[RFC PATCH 34/42] KVM: x86/mmu: add extra param "kvm" to tdp_mmu_map_handle_target_level()

Yan Zhao
2023-12-02T10:01:33Z

Add an extra param "kvm" to tdp_mmu_map_handle_target_level() to allow for
mapping in non-vCPU context in future.

"vcpu" is only required in tdp_mmu_map_handle_target_level() for accounting
of MMIO SPTEs. As kvm_faultin_pfn() now will return error for non-slot
PFNs, no MMIO SPTEs should be generated and accounted in non-vCPU context.
So, just let tdp_mmu_map_handle_target_level() warn if MMIO SPTEs are
encountered in non-vCPU context.

This is a preparation patch for later KVM MMU to export TDP.

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
arch/x86/kvm/mmu/tdp_mmu.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index a45d1b71cd62a..5edff3b4698b7 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -949,7 +949,9 @@ void kvm_tdp_mmu_invalidate_all_roots(struct kvm *kvm)
* Installs a last-level SPTE to handle a TDP page fault.
* (NPT/EPT violation/misconfiguration)
*/
-static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
+static int tdp_mmu_map_handle_target_level(struct kvm *kvm,
+ struct kvm_vcpu *vcpu,
+ struct kvm_mmu_common *mmu_common,
struct kvm_page_fault *fault,
struct tdp_iter *iter)
{
@@ -958,24 +960,26 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
int ret = RET_PF_FIXED;
bool wrprot = false;

+ WARN_ON(!kvm);
+
if (WARN_ON_ONCE(sp->role.level != fault->goal_level))
return RET_PF_RETRY;

if (unlikely(!fault->slot))
new_spte = make_mmio_spte(vcpu->kvm, vcpu, iter->gfn, ACC_ALL);
else
- wrprot = make_spte(vcpu->kvm, vcpu, &vcpu->arch.mmu->common, sp, fault->slot,
+ wrprot = make_spte(kvm, vcpu, mmu_common, sp, fault->slot,
ACC_ALL, iter->gfn, fault->pfn, iter->old_spte,
fault->prefetch, true, fault->map_writable,
&new_spte);

if (new_spte == iter->old_spte)
ret = RET_PF_SPURIOUS;
- else if (tdp_mmu_set_spte_atomic(vcpu->kvm, iter, new_spte))
+ else if (tdp_mmu_set_spte_atomic(kvm, iter, new_spte))
return RET_PF_RETRY;
else if (is_shadow_present_pte(iter->old_spte) &&
!is_last_spte(iter->old_spte, iter->level))
- kvm_flush_remote_tlbs_gfn(vcpu->kvm, iter->gfn, iter->level);
+ kvm_flush_remote_tlbs_gfn(kvm, iter->gfn, iter->level);

/*
* If the page fault was caused by a write but the page is write
@@ -989,10 +993,13 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,

/* If a MMIO SPTE is installed, the MMIO will need to be emulated. */
if (unlikely(is_mmio_spte(new_spte))) {
- vcpu->stat.pf_mmio_spte_created++;
- trace_mark_mmio_spte(rcu_dereference(iter->sptep), iter->gfn,
- new_spte);
- ret = RET_PF_EMULATE;
+ /* if without vcpu, no mmio spte should be installed */
+ if (!WARN_ON(!vcpu)) {
+ vcpu->stat.pf_mmio_spte_created++;
+ trace_mark_mmio_spte(rcu_dereference(iter->sptep), iter->gfn,
+ new_spte);
+ ret = RET_PF_EMULATE;
+ }
} else {
trace_kvm_mmu_set_spte(iter->level, iter->gfn,
rcu_dereference(iter->sptep));
@@ -1114,7 +1121,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
goto retry;

map_target_level:
- ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
+ ret = tdp_mmu_map_handle_target_level(vcpu->kvm, vcpu, &vcpu->arch.mmu->common,
+ fault, &iter);

retry:
rcu_read_unlock();
--
2.17.1