linux-kernel - [RFC PATCH 32/42] KVM: x86/mmu: add extra param "kvm" to make_mmio

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Message-Id: <20231202093119.15407-1-yan.y.zhao@intel.com>
Date:   Sat,  2 Dec 2023 17:31:19 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     alex.williamson@...hat.com, jgg@...dia.com, pbonzini@...hat.com,
        seanjc@...gle.com, joro@...tes.org, will@...nel.org,
        robin.murphy@....com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, dwmw2@...radead.org, yi.l.liu@...el.com,
        Yan Zhao <yan.y.zhao@...el.com>
Subject: [RFC PATCH 32/42] KVM: x86/mmu: add extra param "kvm" to make_mmio_spte()

Add an extra param "kvm" to make_mmio_spte() to allow param "vcpu" to be
NULL in future to allow generating mmio spte in non-vcpu context.

When "vcpu" is NULL, kvm_memslots() rather than kvm_vcpu_memslots() is
called to get memslots pointer, so MMIO SPTEs are not allowed to be
generated for SMM mode in non-vCPU context.

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

Note: actually, if the exported TDP is mapped in non-vCPU context, it
will not reach make_mmio_spte() due to earlier failure in
kvm_handle_noslot_fault(). make_mmio_spte() is modified in this patch to
avoid the check of "vcpu" in the caller.

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 arch/x86/kvm/mmu/mmu.c     | 2 +-
 arch/x86/kvm/mmu/spte.c    | 5 +++--
 arch/x86/kvm/mmu/spte.h    | 2 +-
 arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index df5651ea99139..e4cae4ff20770 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -296,7 +296,7 @@ static void kvm_flush_remote_tlbs_sptep(struct kvm *kvm, u64 *sptep)
 static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
 			   unsigned int access)
 {
-	u64 spte = make_mmio_spte(vcpu, gfn, access);
+	u64 spte = make_mmio_spte(vcpu->kvm, vcpu, gfn, access);
 
 	trace_mark_mmio_spte(sptep, gfn, spte);
 	mmu_spte_set(sptep, spte);
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 9060a56e45569..daeab3b9eee1e 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -71,9 +71,10 @@ static u64 generation_mmio_spte_mask(u64 gen)
 	return mask;
 }
 
-u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access)
+u64 make_mmio_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, u64 gfn, unsigned int access)
 {
-	u64 gen = kvm_vcpu_memslots(vcpu)->generation & MMIO_SPTE_GEN_MASK;
+	struct kvm_memslots *memslots = vcpu ? kvm_vcpu_memslots(vcpu) : kvm_memslots(kvm);
+	u64 gen = memslots->generation & MMIO_SPTE_GEN_MASK;
 	u64 spte = generation_mmio_spte_mask(gen);
 	u64 gpa = gfn << PAGE_SHIFT;
 
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 8f747268a4874..4ad19c469bd73 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -539,7 +539,7 @@ bool make_spte(struct kvm_vcpu *vcpu,
 u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte,
 		      	      union kvm_mmu_page_role role, int index);
 u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
-u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
+u64 make_mmio_spte(struct kvm *kvm, struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
 u64 mark_spte_for_access_track(u64 spte);
 
 /* Restore an acc-track PTE back to a regular PTE */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 5d76d4849e8aa..892cf1f5b57a8 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -962,7 +962,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
 		return RET_PF_RETRY;
 
 	if (unlikely(!fault->slot))
-		new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL);
+		new_spte = make_mmio_spte(vcpu->kvm, vcpu, iter->gfn, ACC_ALL);
 	else
 		wrprot = make_spte(vcpu, &vcpu->arch.mmu->common, sp, fault->slot,
 				   ACC_ALL, iter->gfn, fault->pfn, iter->old_spte,
-- 
2.17.1