[PATCH 12/18] KVM: x86/mmu: Introduce infrastructure to handle non-executable mappings

[Nicolas Saenz Julienne]

The upcoming access restriction KVM memory attributes open the door to
installing non-executable mappings. Introduce a new attribute in struct
kvm_page_fault, map_executable, to control whether the gfn range should
be mapped as executable and make sure it's taken into account when
generating new sptes.

No functional change intended.

Signed-off-by: Nicolas Saenz Julienne <nsa...@amazon.com>
---
 arch/x86/kvm/mmu/mmu.c          | 6 +++++-
 arch/x86/kvm/mmu/mmu_internal.h | 2 ++
 arch/x86/kvm/mmu/tdp_mmu.c      | 8 ++++++--
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 39b113afefdfc..b0c210b96419f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3197,6 +3197,7 @@ void disallowed_hugepage_adjust(struct kvm_page_fault 
*fault, u64 spte, int cur_
 static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 {
        struct kvm_shadow_walk_iterator it;
+       unsigned int access = ACC_ALL;
        struct kvm_mmu_page *sp;
        int ret;
        gfn_t base_gfn = fault->gfn;
@@ -3229,7 +3230,10 @@ static int direct_map(struct kvm_vcpu *vcpu, struct 
kvm_page_fault *fault)
        if (WARN_ON_ONCE(it.level != fault->goal_level))
                return -EFAULT;
 
-       ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL,
+       if (!fault->map_executable)
+               access &= ~ACC_EXEC_MASK;
+
+       ret = mmu_set_spte(vcpu, fault->slot, it.sptep, access,
                           base_gfn, fault->pfn, fault);
        if (ret == RET_PF_SPURIOUS)
                return ret;
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 4f5c4c8af9941..af0c3a154ed89 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -241,6 +241,7 @@ struct kvm_page_fault {
        kvm_pfn_t pfn;
        hva_t hva;
        bool map_writable;
+       bool map_executable;
 
        /*
         * Indicates the guest is trying to write a gfn that contains one or
@@ -313,6 +314,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu 
*vcpu, gpa_t cr2_or_gpa,
 
                .pfn = KVM_PFN_ERR_FAULT,
                .hva = KVM_HVA_ERR_BAD,
+               .map_executable = true,
        };
        int r;
 
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 36539c1b36cd6..344781981999a 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1018,6 +1018,7 @@ static int tdp_mmu_map_handle_target_level(struct 
kvm_vcpu *vcpu,
                                          struct tdp_iter *iter)
 {
        struct kvm_mmu_page *sp = sptep_to_sp(rcu_dereference(iter->sptep));
+       unsigned int access = ACC_ALL;
        u64 new_spte;
        int ret = RET_PF_FIXED;
        bool wrprot = false;
@@ -1025,10 +1026,13 @@ static int tdp_mmu_map_handle_target_level(struct 
kvm_vcpu *vcpu,
        if (WARN_ON_ONCE(sp->role.level != fault->goal_level))
                return RET_PF_RETRY;
 
+       if (!fault->map_executable)
+               access &= ~ACC_EXEC_MASK;
+
        if (unlikely(!fault->slot))
-               new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL);
+               new_spte = make_mmio_spte(vcpu, iter->gfn, access);
        else
-               wrprot = make_spte(vcpu, sp, fault->slot, ACC_ALL, iter->gfn,
+               wrprot = make_spte(vcpu, sp, fault->slot, access, iter->gfn,
                                         fault->pfn, iter->old_spte, 
fault->prefetch, true,
                                         fault->map_writable, &new_spte);
 
-- 
2.40.1