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Message-ID: <20250313203702.575156-15-jon@nutanix.com>
Date: Thu, 13 Mar 2025 13:36:53 -0700
From: Jon Kohler <jon@...anix.com>
To: seanjc@...gle.com, pbonzini@...hat.com, tglx@...utronix.de,
mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
x86@...nel.org, hpa@...or.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Mickaël Salaün <mic@...ikod.net>,
Jon Kohler <jon@...anix.com>
Subject: [RFC PATCH 14/18] KVM: x86/mmu: Extend is_executable_pte to understand MBEC
From: Mickaël Salaün <mic@...ikod.net>
Extend is_executable_pte to understand user vs kernel executable
pages and plumb in kvm_vcpu into kvm_mmu_set_spte so that tracepoints
can tell the right execute permissions.
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Co-developed-by: Jon Kohler <jon@...anix.com>
Signed-off-by: Jon Kohler <jon@...anix.com>
---
arch/x86/kvm/mmu/mmu.c | 11 ++++++-----
arch/x86/kvm/mmu/mmutrace.h | 15 +++++++++------
arch/x86/kvm/mmu/spte.h | 15 +++++++++++++--
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
4 files changed, 29 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 791413b93589..5127520f01d2 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2951,7 +2951,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
ret = RET_PF_SPURIOUS;
} else {
flush |= mmu_spte_update(sptep, spte);
- trace_kvm_mmu_set_spte(level, gfn, sptep);
+ trace_kvm_mmu_set_spte(vcpu, level, gfn, sptep);
}
if (wrprot && write_fault)
@@ -3430,10 +3430,11 @@ static bool fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu,
return true;
}
-static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte)
+static bool is_access_allowed(struct kvm_page_fault *fault, u64 spte,
+ struct kvm_vcpu *vcpu)
{
if (fault->exec)
- return is_executable_pte(spte);
+ return is_executable_pte(spte, !fault->user, vcpu);
if (fault->write)
return is_writable_pte(spte);
@@ -3514,7 +3515,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
* Need not check the access of upper level table entries since
* they are always ACC_ALL.
*/
- if (is_access_allowed(fault, spte)) {
+ if (is_access_allowed(fault, spte, vcpu)) {
ret = RET_PF_SPURIOUS;
break;
}
@@ -3561,7 +3562,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
/* Verify that the fault can be handled in the fast path */
if (new_spte == spte ||
- !is_access_allowed(fault, new_spte))
+ !is_access_allowed(fault, new_spte, vcpu))
break;
/*
diff --git a/arch/x86/kvm/mmu/mmutrace.h b/arch/x86/kvm/mmu/mmutrace.h
index 2511fe64ca01..1067fb7ecd55 100644
--- a/arch/x86/kvm/mmu/mmutrace.h
+++ b/arch/x86/kvm/mmu/mmutrace.h
@@ -339,8 +339,8 @@ TRACE_EVENT(
TRACE_EVENT(
kvm_mmu_set_spte,
- TP_PROTO(int level, gfn_t gfn, u64 *sptep),
- TP_ARGS(level, gfn, sptep),
+ TP_PROTO(struct kvm_vcpu *vcpu, int level, gfn_t gfn, u64 *sptep),
+ TP_ARGS(vcpu, level, gfn, sptep),
TP_STRUCT__entry(
__field(u64, gfn)
@@ -349,7 +349,8 @@ TRACE_EVENT(
__field(u8, level)
/* These depend on page entry type, so compute them now. */
__field(bool, r)
- __field(bool, x)
+ __field(bool, kx)
+ __field(bool, ux)
__field(signed char, u)
),
@@ -359,15 +360,17 @@ TRACE_EVENT(
__entry->sptep = virt_to_phys(sptep);
__entry->level = level;
__entry->r = shadow_present_mask || (__entry->spte & PT_PRESENT_MASK);
- __entry->x = is_executable_pte(__entry->spte);
+ __entry->kx = is_executable_pte(__entry->spte, true, vcpu);
+ __entry->ux = is_executable_pte(__entry->spte, false, vcpu);
__entry->u = shadow_user_mask ? !!(__entry->spte & shadow_user_mask) : -1;
),
- TP_printk("gfn %llx spte %llx (%s%s%s%s) level %d at %llx",
+ TP_printk("gfn %llx spte %llx (%s%s%s%s%s) level %d at %llx",
__entry->gfn, __entry->spte,
__entry->r ? "r" : "-",
__entry->spte & PT_WRITABLE_MASK ? "w" : "-",
- __entry->x ? "x" : "-",
+ __entry->kx ? "X" : "-",
+ __entry->ux ? "x" : "-",
__entry->u == -1 ? "" : (__entry->u ? "u" : "-"),
__entry->level, __entry->sptep
)
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 1f7b388a56aa..fd7e29a0a567 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -346,9 +346,20 @@ static inline bool is_last_spte(u64 pte, int level)
return (level == PG_LEVEL_4K) || is_large_pte(pte);
}
-static inline bool is_executable_pte(u64 spte)
+static inline bool is_executable_pte(u64 spte, bool for_kernel_mode,
+ struct kvm_vcpu *vcpu)
{
- return (spte & (shadow_x_mask | shadow_nx_mask)) == shadow_x_mask;
+ u64 x_mask = shadow_x_mask;
+
+ if (vcpu->arch.pt_guest_exec_control) {
+ x_mask |= shadow_ux_mask;
+ if (for_kernel_mode)
+ x_mask &= ~VMX_EPT_USER_EXECUTABLE_MASK;
+ else
+ x_mask &= ~VMX_EPT_EXECUTABLE_MASK;
+ }
+
+ return (spte & (x_mask | shadow_nx_mask)) == x_mask;
}
static inline kvm_pfn_t spte_to_pfn(u64 pte)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 3b996c1fdaab..6a799ab42687 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1056,7 +1056,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
new_spte);
ret = RET_PF_EMULATE;
} else {
- trace_kvm_mmu_set_spte(iter->level, iter->gfn,
+ trace_kvm_mmu_set_spte(vcpu, iter->level, iter->gfn,
rcu_dereference(iter->sptep));
}
--
2.43.0
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