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Message-Id: <20240227232100.478238-4-pbonzini@redhat.com>
Date: Tue, 27 Feb 2024 18:20:42 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: seanjc@...gle.com,
michael.roth@....com,
isaku.yamahata@...el.com,
thomas.lendacky@....com
Subject: [PATCH 03/21] KVM: x86/mmu: Replace hardcoded value 0 for the initial value for SPTE
From: Sean Christopherson <seanjc@...gle.com>
The TDX support will need the "suppress #VE" bit (bit 63) set as the
initial value for SPTE. To reduce code change size, introduce a new macro
SHADOW_NONPRESENT_VALUE for the initial value for the shadow page table
entry (SPTE) and replace hard-coded value 0 for it. Initialize shadow page
tables with their value.
The plan is to unconditionally set the "suppress #VE" bit for both AMD and
Intel as: 1) AMD hardware uses the bit 63 as NX for present SPTE and
ignored for non-present SPTE; 2) for conventional VMX guests, KVM never
enables the "EPT-violation #VE" in VMCS control and "suppress #VE" bit is
ignored by hardware.
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Message-Id: <acdf09bf60cad12c495005bf3495c54f6b3069c9.1705965635.git.isaku.yamahata@...el.com>
[Remove unnecessary CONFIG_X86_64 check. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
arch/x86/kvm/mmu/mmu.c | 14 +++++++++-----
arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
arch/x86/kvm/mmu/spte.h | 2 ++
arch/x86/kvm/mmu/tdp_mmu.c | 14 +++++++-------
4 files changed, 19 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e4cc7f764980..b5baf11359ad 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -567,9 +567,9 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep)
if (!is_shadow_present_pte(old_spte) ||
!spte_has_volatile_bits(old_spte))
- __update_clear_spte_fast(sptep, 0ull);
+ __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE);
else
- old_spte = __update_clear_spte_slow(sptep, 0ull);
+ old_spte = __update_clear_spte_slow(sptep, SHADOW_NONPRESENT_VALUE);
if (!is_shadow_present_pte(old_spte))
return old_spte;
@@ -603,7 +603,7 @@ static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep)
*/
static void mmu_spte_clear_no_track(u64 *sptep)
{
- __update_clear_spte_fast(sptep, 0ull);
+ __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE);
}
static u64 mmu_spte_get_lockless(u64 *sptep)
@@ -1950,7 +1950,8 @@ static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
static int kvm_sync_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i)
{
- if (!sp->spt[i])
+ /* sp->spt[i] has initial value of shadow page table allocation */
+ if (sp->spt[i] == SHADOW_NONPRESENT_VALUE)
return 0;
return vcpu->arch.mmu->sync_spte(vcpu, sp, i);
@@ -6173,7 +6174,10 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
- vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_shadow_page_cache.init_value =
+ SHADOW_NONPRESENT_VALUE;
+ if (!vcpu->arch.mmu_shadow_page_cache.init_value)
+ vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
vcpu->arch.mmu = &vcpu->arch.root_mmu;
vcpu->arch.walk_mmu = &vcpu->arch.root_mmu;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 4d4e98fe4f35..bebd73cd61bb 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -911,7 +911,7 @@ static int FNAME(sync_spte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int
gpa_t pte_gpa;
gfn_t gfn;
- if (WARN_ON_ONCE(!sp->spt[i]))
+ if (WARN_ON_ONCE(sp->spt[i] == SHADOW_NONPRESENT_VALUE))
return 0;
first_pte_gpa = FNAME(get_level1_sp_gpa)(sp);
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index a129951c9a88..4d1799ba2bf8 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -149,6 +149,8 @@ static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11);
#define MMIO_SPTE_GEN_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0)
+#define SHADOW_NONPRESENT_VALUE 0ULL
+
extern u64 __read_mostly shadow_host_writable_mask;
extern u64 __read_mostly shadow_mmu_writable_mask;
extern u64 __read_mostly shadow_nx_mask;
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index d078157e62aa..c8a4d92497b4 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -603,7 +603,7 @@ static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm,
* here since the SPTE is going from non-present to non-present. Use
* the raw write helper to avoid an unnecessary check on volatile bits.
*/
- __kvm_tdp_mmu_write_spte(iter->sptep, 0);
+ __kvm_tdp_mmu_write_spte(iter->sptep, SHADOW_NONPRESENT_VALUE);
return 0;
}
@@ -740,8 +740,8 @@ static void __tdp_mmu_zap_root(struct kvm *kvm, struct kvm_mmu_page *root,
continue;
if (!shared)
- tdp_mmu_iter_set_spte(kvm, &iter, 0);
- else if (tdp_mmu_set_spte_atomic(kvm, &iter, 0))
+ tdp_mmu_iter_set_spte(kvm, &iter, SHADOW_NONPRESENT_VALUE);
+ else if (tdp_mmu_set_spte_atomic(kvm, &iter, SHADOW_NONPRESENT_VALUE))
goto retry;
}
}
@@ -808,8 +808,8 @@ bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
if (WARN_ON_ONCE(!is_shadow_present_pte(old_spte)))
return false;
- tdp_mmu_set_spte(kvm, kvm_mmu_page_as_id(sp), sp->ptep, old_spte, 0,
- sp->gfn, sp->role.level + 1);
+ tdp_mmu_set_spte(kvm, kvm_mmu_page_as_id(sp), sp->ptep, old_spte,
+ SHADOW_NONPRESENT_VALUE, sp->gfn, sp->role.level + 1);
return true;
}
@@ -843,7 +843,7 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root,
!is_last_spte(iter.old_spte, iter.level))
continue;
- tdp_mmu_iter_set_spte(kvm, &iter, 0);
+ tdp_mmu_iter_set_spte(kvm, &iter, SHADOW_NONPRESENT_VALUE);
/*
* Zappings SPTEs in invalid roots doesn't require a TLB flush,
@@ -1276,7 +1276,7 @@ static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter,
* invariant that the PFN of a present * leaf SPTE can never change.
* See handle_changed_spte().
*/
- tdp_mmu_iter_set_spte(kvm, iter, 0);
+ tdp_mmu_iter_set_spte(kvm, iter, SHADOW_NONPRESENT_VALUE);
if (!pte_write(range->arg.pte)) {
new_spte = kvm_mmu_changed_pte_notifier_make_spte(iter->old_spte,
--
2.39.0
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