From: Chao Gao <chao.gao@intel.com>
To: Xin Li <xin3.li@intel.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
"seanjc@google.com" <seanjc@google.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"corbet@lwn.net" <corbet@lwn.net>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"shuah@kernel.org" <shuah@kernel.org>,
"vkuznets@redhat.com" <vkuznets@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
"xin@zytor.com" <xin@zytor.com>
Subject: Re: [PATCH v2 13/25] KVM: VMX: Handle VMX nested exception for FRED
Date: Tue, 30 Apr 2024 15:34:08 +0800 [thread overview]
Message-ID: <ZjCe8HGMh1D8KXdD@chao-email> (raw)
In-Reply-To: <20240207172646.3981-14-xin3.li@intel.com>
On Thu, Feb 08, 2024 at 01:26:33AM +0800, Xin Li wrote:
>Set VMX nested exception bit in the VM-entry interruption information
>VMCS field when injecting a nested exception using FRED event delivery
>to ensure:
> 1) The nested exception is injected on a correct stack level.
> 2) The nested bit defined in FRED stack frame is set.
>
>The event stack level used by FRED event delivery depends on whether the
>event was a nested exception encountered during delivery of another event,
>because a nested exception is "regarded" as happening on ring 0. E.g.,
>when #PF is configured to use stack level 1 in IA32_FRED_STKLVLS MSR:
> - nested #PF will be delivered on stack level 1 when encountered in
> ring 3.
> - normal #PF will be delivered on stack level 0 when encountered in
> ring 3.
>
>The VMX nested-exception support ensures the correct event stack level is
>chosen when a VM entry injects a nested exception.
>
>Signed-off-by: Xin Li <xin3.li@intel.com>
>Tested-by: Shan Kang <shan.kang@intel.com>
>---
>
>Changes since v1:
>* Set the nested flag when there is an original interrupt (Chao Gao).
>---
> arch/x86/include/asm/kvm_host.h | 6 +++--
> arch/x86/include/asm/vmx.h | 5 ++--
> arch/x86/kvm/svm/svm.c | 4 +--
> arch/x86/kvm/vmx/vmx.c | 8 ++++--
> arch/x86/kvm/x86.c | 46 ++++++++++++++++++++++++++-------
> arch/x86/kvm/x86.h | 1 +
> 6 files changed, 53 insertions(+), 17 deletions(-)
>
>diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>index 0d88873eba63..ef278ee0b6ca 100644
>--- a/arch/x86/include/asm/kvm_host.h
>+++ b/arch/x86/include/asm/kvm_host.h
>@@ -736,6 +736,7 @@ struct kvm_queued_exception {
> u32 error_code;
> unsigned long payload;
> bool has_payload;
>+ bool nested;
"nested" may be lost after migration.
> };
>
> struct kvm_vcpu_arch {
>@@ -2060,8 +2061,9 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu);
> void kvm_queue_exception(struct kvm_vcpu *vcpu, unsigned nr);
> void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
> void kvm_queue_exception_p(struct kvm_vcpu *vcpu, unsigned nr, unsigned long payload);
>-void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
>-void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
>+void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr, bool nested);
>+void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr,
>+ u32 error_code, bool nested);
> void kvm_inject_page_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault);
> void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
> struct x86_exception *fault);
>diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
>index 6b796c5c9c2b..68af74e48788 100644
>--- a/arch/x86/include/asm/vmx.h
>+++ b/arch/x86/include/asm/vmx.h
>@@ -134,7 +134,7 @@
> #define VMX_BASIC_DUAL_MONITOR_TREATMENT BIT_ULL(49)
> #define VMX_BASIC_INOUT BIT_ULL(54)
> #define VMX_BASIC_TRUE_CTLS BIT_ULL(55)
>-
>+#define VMX_BASIC_NESTED_EXCEPTION BIT_ULL(58)
this definition is not used in this patch.
>
> /* VMX_MISC bits and bitmasks */
> #define VMX_MISC_INTEL_PT BIT_ULL(14)
>@@ -407,8 +407,9 @@ enum vmcs_field {
> #define INTR_INFO_INTR_TYPE_MASK 0x700 /* 10:8 */
> #define INTR_INFO_DELIVER_CODE_MASK 0x800 /* 11 */
> #define INTR_INFO_UNBLOCK_NMI 0x1000 /* 12 */
>+#define INTR_INFO_NESTED_EXCEPTION_MASK 0x2000 /* 13 */
> #define INTR_INFO_VALID_MASK 0x80000000 /* 31 */
>-#define INTR_INFO_RESVD_BITS_MASK 0x7ffff000
>+#define INTR_INFO_RESVD_BITS_MASK 0x7fffd000
>
> #define VECTORING_INFO_VECTOR_MASK INTR_INFO_VECTOR_MASK
> #define VECTORING_INFO_TYPE_MASK INTR_INFO_INTR_TYPE_MASK
>diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>index e90b429c84f1..c220b690a37c 100644
>--- a/arch/x86/kvm/svm/svm.c
>+++ b/arch/x86/kvm/svm/svm.c
>@@ -4057,10 +4057,10 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu)
>
> if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
> u32 err = svm->vmcb->control.exit_int_info_err;
>- kvm_requeue_exception_e(vcpu, vector, err);
>+ kvm_requeue_exception_e(vcpu, vector, err, false);
>
> } else
>- kvm_requeue_exception(vcpu, vector);
>+ kvm_requeue_exception(vcpu, vector, false);
> break;
> case SVM_EXITINTINFO_TYPE_INTR:
> kvm_queue_interrupt(vcpu, vector, false);
>diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>index f622fb90a098..1f265d526daf 100644
>--- a/arch/x86/kvm/vmx/vmx.c
>+++ b/arch/x86/kvm/vmx/vmx.c
>@@ -1891,6 +1891,8 @@ static void vmx_inject_exception(struct kvm_vcpu *vcpu)
> event_data = to_vmx(vcpu)->fred_xfd_event_data;
>
> vmcs_write64(INJECTED_EVENT_DATA, event_data);
>+
>+ intr_info |= ex->nested ? INTR_INFO_NESTED_EXCEPTION_MASK : 0;
> }
> }
>
>@@ -7281,9 +7283,11 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, bool vectoring)
> }
>
> if (event_id & INTR_INFO_DELIVER_CODE_MASK)
>- kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field));
>+ kvm_requeue_exception_e(vcpu, vector, vmcs_read32(error_code_field),
>+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
> else
>- kvm_requeue_exception(vcpu, vector);
>+ kvm_requeue_exception(vcpu, vector,
>+ event_id & INTR_INFO_NESTED_EXCEPTION_MASK);
> break;
> case INTR_TYPE_SOFT_INTR:
> vcpu->arch.event_exit_inst_len = vmcs_read32(instr_len_field);
>diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>index 00c0062726ae..725819262085 100644
>--- a/arch/x86/kvm/x86.c
>+++ b/arch/x86/kvm/x86.c
>@@ -645,7 +645,8 @@ static void kvm_leave_nested(struct kvm_vcpu *vcpu)
>
> static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> unsigned nr, bool has_error, u32 error_code,
>- bool has_payload, unsigned long payload, bool reinject)
>+ bool has_payload, unsigned long payload,
>+ bool reinject, bool nested)
> {
> u32 prev_nr;
> int class1, class2;
>@@ -696,6 +697,13 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.pending = true;
> vcpu->arch.exception.injected = false;
> }
>+
>+ vcpu->arch.exception.nested = vcpu->arch.exception.nested ||
>+ (kvm_is_fred_enabled(vcpu) &&
>+ ((reinject && nested) ||
>+ vcpu->arch.nmi_injected ||
>+ vcpu->arch.interrupt.injected));
You can set the nested flag regardless of FRED because the sole place using
such information (vmx_inject_exception()) is guarded by kvm_is_fred_enabled()
already.
I would also drop the check about @reinject to make @reinject and @nested
orthogonal (i.e., avoid the artifical rule that nested interrupts should be
queued by "reinject" only)
so, how about:
if (vcpu->arch.nmi_injected || vcpu->arch.interrupt.injected ||
nested)
vcpu->arch.exception.nested = true;
>+
> vcpu->arch.exception.has_error_code = has_error;
> vcpu->arch.exception.vector = nr;
> vcpu->arch.exception.error_code = error_code;
>@@ -725,8 +733,28 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> vcpu->arch.exception.injected = false;
> vcpu->arch.exception.pending = false;
>
>+ /*
>+ * A #DF is NOT a nested event per its definition, however per
>+ * FRED spec 5.0 Appendix B, its delivery determines the new
>+ * stack level as is done for events occurring when CPL = 0.
>+ */
>+ vcpu->arch.exception.nested = false;
>+
> kvm_queue_exception_e(vcpu, DF_VECTOR, 0);
> } else {
>+ /*
>+ * FRED spec 5.0 Appendix B: delivery of a nested exception
>+ * determines the new stack level as is done for events
>+ * occurring when CPL = 0.
>+ *
>+ * IOW, FRED event delivery of an event encountered in ring 3
>+ * normally uses stack level 0 unconditionally. However, if
>+ * the event is an exception nested on any earlier event,
>+ * delivery of the nested exception will consult the FRED MSR
>+ * IA32_FRED_STKLVLS to determine which stack level to use.
>+ */
>+ vcpu->arch.exception.nested = kvm_is_fred_enabled(vcpu);
as said above, nested flag can be set regardless of FRED.
next prev parent reply other threads:[~2024-04-30 7:34 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 17:26 [PATCH v2 00/25] Enable FRED with KVM VMX Xin Li
2024-02-07 17:26 ` [PATCH v2 01/25] KVM: VMX: Cleanup VMX basic information defines and usages Xin Li
2024-02-07 17:26 ` [PATCH v2 02/25] KVM: VMX: Cleanup VMX misc " Xin Li
2024-02-07 17:26 ` [PATCH v2 03/25] KVM: VMX: Add support for the secondary VM exit controls Xin Li
2024-04-19 10:21 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 04/25] KVM: x86: Mark CR4.FRED as not reserved Xin Li
2024-04-19 10:22 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 05/25] KVM: VMX: Initialize FRED VM entry/exit controls in vmcs_config Xin Li
2024-04-19 10:24 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 06/25] KVM: VMX: Defer enabling FRED MSRs save/load until after set CPUID Xin Li
2024-04-19 11:02 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 07/25] KVM: VMX: Set intercept for FRED MSRs Xin Li
2024-04-19 13:35 ` Chao Gao
2024-04-19 17:06 ` Li, Xin3
2024-02-07 17:26 ` [PATCH v2 08/25] KVM: VMX: Initialize VMCS FRED fields Xin Li
2024-04-19 14:01 ` Chao Gao
2024-04-19 17:02 ` Li, Xin3
2024-02-07 17:26 ` [PATCH v2 09/25] KVM: VMX: Switch FRED RSP0 between host and guest Xin Li
2024-04-19 14:23 ` Chao Gao
2024-04-19 16:37 ` Li, Xin3
2024-02-07 17:26 ` [PATCH v2 10/25] KVM: VMX: Add support for FRED context save/restore Xin Li
2024-04-29 6:31 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 11/25] KVM: x86: Add kvm_is_fred_enabled() Xin Li
2024-04-29 8:24 ` Chao Gao
2024-05-11 1:24 ` Li, Xin3
2024-05-11 1:53 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 12/25] KVM: VMX: Handle FRED event data Xin Li
2024-04-30 3:14 ` Chao Gao
2024-05-10 9:36 ` Li, Xin3
2024-05-11 3:03 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 13/25] KVM: VMX: Handle VMX nested exception for FRED Xin Li
2024-04-30 7:34 ` Chao Gao [this message]
2024-02-07 17:26 ` [PATCH v2 14/25] KVM: VMX: Disable FRED if FRED consistency checks fail Xin Li
2024-04-30 8:21 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 15/25] KVM: VMX: Dump FRED context in dump_vmcs() Xin Li
2024-04-30 9:09 ` Chao Gao
2024-02-07 17:26 ` [PATCH v2 16/25] KVM: VMX: Invoke vmx_set_cpu_caps() before nested setup Xin Li
2024-02-07 17:26 ` [PATCH v2 17/25] KVM: nVMX: Add support for the secondary VM exit controls Xin Li
2024-02-07 17:26 ` [PATCH v2 18/25] KVM: nVMX: Add a prerequisite to SHADOW_FIELD_R[OW] macros Xin Li
2024-02-07 17:26 ` [PATCH v2 19/25] KVM: nVMX: Add FRED VMCS fields Xin Li
2024-02-07 17:26 ` [PATCH v2 20/25] KVM: nVMX: Add support for VMX FRED controls Xin Li
2024-02-07 17:26 ` [PATCH v2 21/25] KVM: nVMX: Add VMCS FRED states checking Xin Li
2024-02-07 17:26 ` [PATCH v2 22/25] KVM: x86: Allow FRED/LKGS/WRMSRNS to be exposed to guests Xin Li
2024-02-07 17:26 ` [PATCH v2 23/25] KVM: selftests: Run debug_regs test with FRED enabled Xin Li
2024-02-07 17:26 ` [PATCH v2 24/25] KVM: selftests: Add a new VM guest mode to run user level code Xin Li
2024-02-07 17:26 ` [PATCH v2 25/25] KVM: selftests: Add fred exception tests Xin Li
2024-03-29 20:18 ` Muhammad Usama Anjum
2024-03-29 20:18 ` Muhammad Usama Anjum
2024-04-24 16:08 ` Sean Christopherson
2024-03-27 8:08 ` [PATCH v2 00/25] Enable FRED with KVM VMX Kang, Shan
2024-04-15 17:58 ` Li, Xin3
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