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Message-Id: <d8447d317d5fee37b0cff586ecc3a8bc3da94984.1605232743.git.isaku.yamahata@intel.com>
Date: Mon, 16 Nov 2020 10:26:23 -0800
From: isaku.yamahata@...el.com
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>, x86@...nel.org,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com, isaku.yamahata@...il.com,
Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [RFC PATCH 38/67] KVM: x86/mmu: Allow non-zero init value for shadow PTE
From: Sean Christopherson <sean.j.christopherson@...el.com>
TDX will run with EPT violation #VEs enabled, which means KVM needs to
set the "suppress #VE" bit in unused PTEs to avoid unintentionally
reflecting not-present EPT violations into the guest.
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
arch/x86/kvm/mmu.h | 1 +
arch/x86/kvm/mmu/mmu.c | 50 +++++++++++++++++++++++++++++++++++------
arch/x86/kvm/mmu/spte.c | 10 +++++++++
arch/x86/kvm/mmu/spte.h | 2 ++
4 files changed, 56 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 05c2898cb2a2..e9598a51090b 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -55,6 +55,7 @@ static inline u64 rsvd_bits(int s, int e)
void kvm_mmu_set_mmio_spte_mask(struct kvm *kvm, u64 mmio_value,
u64 access_mask);
void kvm_mmu_set_default_mmio_spte_mask(u64 mask);
+void kvm_mmu_set_spte_init_value(u64 init_value);
void
reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index da2a58fa86a8..732510ecda36 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -560,9 +560,9 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
u64 old_spte = *sptep;
if (!spte_has_volatile_bits(old_spte))
- __update_clear_spte_fast(sptep, 0ull);
+ __update_clear_spte_fast(sptep, shadow_init_value);
else
- old_spte = __update_clear_spte_slow(sptep, 0ull);
+ old_spte = __update_clear_spte_slow(sptep, shadow_init_value);
if (!is_shadow_present_pte(old_spte))
return 0;
@@ -592,7 +592,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep)
*/
static void mmu_spte_clear_no_track(u64 *sptep)
{
- __update_clear_spte_fast(sptep, 0ull);
+ __update_clear_spte_fast(sptep, shadow_init_value);
}
static u64 mmu_spte_get_lockless(u64 *sptep)
@@ -670,6 +670,42 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
local_irq_enable();
}
+static inline void kvm_init_shadow_page(void *page)
+{
+#ifdef CONFIG_X86_64
+ int ign;
+
+ asm volatile (
+ "rep stosq\n\t"
+ : "=c"(ign), "=D"(page)
+ : "a"(shadow_init_value), "c"(4096/8), "D"(page)
+ : "memory"
+ );
+#else
+ BUG();
+#endif
+}
+
+static int mmu_topup_shadow_page_cache(struct kvm_vcpu *vcpu)
+{
+ struct kvm_mmu_memory_cache *mc = &vcpu->arch.mmu_shadow_page_cache;
+ int start, end, i, r;
+
+ if (shadow_init_value)
+ start = kvm_mmu_memory_cache_nr_free_objects(mc);
+
+ r = kvm_mmu_topup_memory_cache(mc, PT64_ROOT_MAX_LEVEL);
+ if (r)
+ return r;
+
+ if (shadow_init_value) {
+ end = kvm_mmu_memory_cache_nr_free_objects(mc);
+ for (i = start; i < end; i++)
+ kvm_init_shadow_page(mc->objects[i]);
+ }
+ return 0;
+}
+
static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
{
int r;
@@ -679,8 +715,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM);
if (r)
return r;
- r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache,
- PT64_ROOT_MAX_LEVEL);
+ r = mmu_topup_shadow_page_cache(vcpu);
if (r)
return r;
if (maybe_indirect) {
@@ -3074,7 +3109,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
struct kvm_shadow_walk_iterator iterator;
struct kvm_mmu_page *sp;
int ret = RET_PF_INVALID;
- u64 spte = 0ull;
+ u64 spte = shadow_init_value;
uint retry_count = 0;
if (!page_fault_can_be_fast(error_code))
@@ -5356,7 +5391,8 @@ 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;
+ if (!shadow_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/spte.c b/arch/x86/kvm/mmu/spte.c
index 574c8ccac0bf..079bbef7b8aa 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -27,6 +27,7 @@ u64 __read_mostly shadow_mmio_access_mask;
u64 __read_mostly shadow_present_mask;
u64 __read_mostly shadow_me_mask;
u64 __read_mostly shadow_acc_track_mask;
+u64 __read_mostly shadow_init_value;
u64 __read_mostly shadow_nonpresent_or_rsvd_mask;
u64 __read_mostly shadow_nonpresent_or_rsvd_lower_gfn_mask;
@@ -195,6 +196,14 @@ u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn)
return new_spte;
}
+void kvm_mmu_set_spte_init_value(u64 init_value)
+{
+ if (WARN_ON(!IS_ENABLED(CONFIG_X86_64) && init_value))
+ init_value = 0;
+ shadow_init_value = init_value;
+}
+EXPORT_SYMBOL_GPL(kvm_mmu_set_spte_init_value);
+
static u8 kvm_get_shadow_phys_bits(void)
{
/*
@@ -291,6 +300,7 @@ void kvm_mmu_reset_all_pte_masks(void)
shadow_present_mask = 0;
shadow_acc_track_mask = 0;
shadow_default_mmio_mask = 0;
+ shadow_init_value = 0;
shadow_phys_bits = kvm_get_shadow_phys_bits();
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 22256cc8cce6..a5eab5607606 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -91,6 +91,8 @@ extern u64 __read_mostly shadow_mmio_access_mask;
extern u64 __read_mostly shadow_present_mask;
extern u64 __read_mostly shadow_me_mask;
+extern u64 __read_mostly shadow_init_value;
+
/*
* SPTEs used by MMUs without A/D bits are marked with SPTE_AD_DISABLED_MASK;
* shadow_acc_track_mask is the set of bits to be cleared in non-accessed
--
2.17.1
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