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Message-ID: <20250424030800.452-1-yan.y.zhao@intel.com>
Date: Thu, 24 Apr 2025 11:08:00 +0800
From: Yan Zhao <yan.y.zhao@...el.com>
To: pbonzini@...hat.com,
seanjc@...gle.com
Cc: linux-kernel@...r.kernel.org,
kvm@...r.kernel.org,
x86@...nel.org,
rick.p.edgecombe@...el.com,
dave.hansen@...el.com,
kirill.shutemov@...el.com,
tabba@...gle.com,
ackerleytng@...gle.com,
quic_eberman@...cinc.com,
michael.roth@....com,
david@...hat.com,
vannapurve@...gle.com,
vbabka@...e.cz,
jroedel@...e.de,
thomas.lendacky@....com,
pgonda@...gle.com,
zhiquan1.li@...el.com,
fan.du@...el.com,
jun.miao@...el.com,
ira.weiny@...el.com,
isaku.yamahata@...el.com,
xiaoyao.li@...el.com,
binbin.wu@...ux.intel.com,
chao.p.peng@...el.com,
Yan Zhao <yan.y.zhao@...el.com>
Subject: [RFC PATCH 15/21] KVM: TDX: Support huge page splitting with exclusive kvm->mmu_lock
From: Xiaoyao Li <xiaoyao.li@...el.com>
Implement the split_external_spt hook to support huge page splitting for
TDX when kvm->mmu_lock is held for writing.
Invoke tdh_mem_range_block(), tdh_mem_track(), kicking off vCPUs,
tdh_mem_page_demote() in sequence. Since kvm->mmu_lock is held for writing,
simply kick off vCPUs on tdx_operand_busy() to ensure the second SEAMCALL
invocation succeeds.
TDX module may return TDX_INTERRUPTED_RESTARTABLE when there is a pending
interrupt on the host side during tdh_mem_page_demote(). Retry indefinitely
on this error, as with exclusive kvm->mmu_lock the pending interrupt is for
host only.
[Yan: Split patch for exclusive mmu_lock only, handled busy error ]
Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
arch/x86/kvm/vmx/main.c | 1 +
arch/x86/kvm/vmx/tdx.c | 45 ++++++++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/tdx_errno.h | 1 +
arch/x86/kvm/vmx/x86_ops.h | 9 ++++++++
4 files changed, 56 insertions(+)
diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index ae8540576821..16c0c31dd066 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -62,6 +62,7 @@ static __init int vt_hardware_setup(void)
vt_x86_ops.set_external_spte = tdx_sept_set_private_spte;
vt_x86_ops.free_external_spt = tdx_sept_free_private_spt;
vt_x86_ops.remove_external_spte = tdx_sept_remove_private_spte;
+ vt_x86_ops.split_external_spt = tdx_sept_split_private_spt;
vt_x86_ops.protected_apic_has_interrupt = tdx_protected_apic_has_interrupt;
}
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index dd63a634e633..4386e1a0323e 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1806,6 +1806,51 @@ int tdx_sept_free_private_spt(struct kvm *kvm, gfn_t gfn,
return tdx_reclaim_page(virt_to_page(private_spt), PG_LEVEL_4K);
}
+static int tdx_spte_demote_private_spte(struct kvm *kvm, gfn_t gfn,
+ enum pg_level level, struct page *page)
+{
+ int tdx_level = pg_level_to_tdx_sept_level(level);
+ struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
+ gpa_t gpa = gfn_to_gpa(gfn);
+ u64 err, entry, level_state;
+
+ do {
+ err = tdh_mem_page_demote(&kvm_tdx->td, gpa, tdx_level, page,
+ &entry, &level_state);
+ } while (err == TDX_INTERRUPTED_RESTARTABLE);
+
+ if (unlikely(tdx_operand_busy(err))) {
+ tdx_no_vcpus_enter_start(kvm);
+ err = tdh_mem_page_demote(&kvm_tdx->td, gpa, tdx_level, page,
+ &entry, &level_state);
+ tdx_no_vcpus_enter_stop(kvm);
+ }
+
+ if (KVM_BUG_ON(err, kvm)) {
+ pr_tdx_error_2(TDH_MEM_PAGE_DEMOTE, err, entry, level_state);
+ return -EIO;
+ }
+ return 0;
+}
+
+int tdx_sept_split_private_spt(struct kvm *kvm, gfn_t gfn, enum pg_level level,
+ void *private_spt)
+{
+ struct page *page = virt_to_page(private_spt);
+ int ret;
+
+ if (KVM_BUG_ON(to_kvm_tdx(kvm)->state != TD_STATE_RUNNABLE || level != PG_LEVEL_2M, kvm))
+ return -EINVAL;
+
+ ret = tdx_sept_zap_private_spte(kvm, gfn, level, page);
+ if (ret <= 0)
+ return ret;
+
+ tdx_track(kvm);
+
+ return tdx_spte_demote_private_spte(kvm, gfn, level, page);
+}
+
int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, kvm_pfn_t pfn)
{
diff --git a/arch/x86/kvm/vmx/tdx_errno.h b/arch/x86/kvm/vmx/tdx_errno.h
index 6ff4672c4181..33589e7fa1e1 100644
--- a/arch/x86/kvm/vmx/tdx_errno.h
+++ b/arch/x86/kvm/vmx/tdx_errno.h
@@ -14,6 +14,7 @@
#define TDX_NON_RECOVERABLE_TD_NON_ACCESSIBLE 0x6000000500000000ULL
#define TDX_NON_RECOVERABLE_TD_WRONG_APIC_MODE 0x6000000700000000ULL
#define TDX_INTERRUPTED_RESUMABLE 0x8000000300000000ULL
+#define TDX_INTERRUPTED_RESTARTABLE 0x8000000400000000ULL
#define TDX_OPERAND_INVALID 0xC000010000000000ULL
#define TDX_OPERAND_BUSY 0x8000020000000000ULL
#define TDX_PREVIOUS_TLB_EPOCH_BUSY 0x8000020100000000ULL
diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
index 7c183da7c4d4..df7d4cd1436c 100644
--- a/arch/x86/kvm/vmx/x86_ops.h
+++ b/arch/x86/kvm/vmx/x86_ops.h
@@ -158,6 +158,8 @@ int tdx_sept_set_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, kvm_pfn_t pfn);
int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
enum pg_level level, kvm_pfn_t pfn);
+int tdx_sept_split_private_spt(struct kvm *kvm, gfn_t gfn, enum pg_level level,
+ void *private_spt);
void tdx_flush_tlb_current(struct kvm_vcpu *vcpu);
void tdx_flush_tlb_all(struct kvm_vcpu *vcpu);
@@ -224,6 +226,13 @@ static inline int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn,
return -EOPNOTSUPP;
}
+static inline int tdx_sept_split_private_spt(struct kvm *kvm, gfn_t gfn,
+ enum pg_level level,
+ void *private_spt)
+{
+ return -EOPNOTSUPP;
+}
+
static inline void tdx_flush_tlb_current(struct kvm_vcpu *vcpu) {}
static inline void tdx_flush_tlb_all(struct kvm_vcpu *vcpu) {}
static inline void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level) {}
--
2.43.2
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