diff mbox series

[RFC,v6,40/92] KVM: VMX: Handle SPP induced vmexit and page fault

Message ID 20190809160047.8319-41-alazar@bitdefender.com
State New, archived
Headers show
Series VM introspection | expand

Commit Message

Adalbert Lazăr Aug. 9, 2019, 3:59 p.m. UTC
From: Yang Weijiang <weijiang.yang@intel.com>

If write to subpage is not allowed, EPT violation is generated,
it's propagated to QEMU or VMI to handle.

If the target page is SPP protected, however SPPT missing is
encoutered while traversing with gfn, vmexit is generated so
that KVM can handle the issue. Any SPPT misconfig will be
propagated to QEMU or VMI.

A SPP specific bit(11) is added to exit_qualification and a new
exit reason(66) is introduced for SPP.

Co-developed-by: He Chen <he.chen@linux.intel.com>
Signed-off-by: He Chen <he.chen@linux.intel.com>
Co-developed-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com>
Co-developed-by: Yang Weijiang <weijiang.yang@intel.com>
Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Message-Id: <20190717133751.12910-8-weijiang.yang@intel.com>
Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
---
 arch/x86/include/asm/vmx.h      |  7 ++++
 arch/x86/include/uapi/asm/vmx.h |  2 +
 arch/x86/kvm/mmu.c              | 17 ++++++++
 arch/x86/kvm/vmx/vmx.c          | 71 +++++++++++++++++++++++++++++++++
 include/uapi/linux/kvm.h        |  5 +++
 5 files changed, 102 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 6cb05ac07453..11ca64ced578 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -547,6 +547,13 @@  struct vmx_msr_entry {
 #define EPT_VIOLATION_EXECUTABLE	(1 << EPT_VIOLATION_EXECUTABLE_BIT)
 #define EPT_VIOLATION_GVA_TRANSLATED	(1 << EPT_VIOLATION_GVA_TRANSLATED_BIT)
 
+/*
+ * Exit Qualifications for SPPT-Induced vmexits
+ */
+#define SPPT_INDUCED_EXIT_TYPE_BIT     11
+#define SPPT_INDUCED_EXIT_TYPE         (1 << SPPT_INDUCED_EXIT_TYPE_BIT)
+#define SPPT_INTR_INFO_UNBLOCK_NMI     INTR_INFO_UNBLOCK_NMI
+
 /*
  * VM-instruction error numbers
  */
diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index f0b0c90dd398..ac67622bac5a 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -85,6 +85,7 @@ 
 #define EXIT_REASON_PML_FULL            62
 #define EXIT_REASON_XSAVES              63
 #define EXIT_REASON_XRSTORS             64
+#define EXIT_REASON_SPP                 66
 
 #define VMX_EXIT_REASONS \
 	{ EXIT_REASON_EXCEPTION_NMI,         "EXCEPTION_NMI" }, \
@@ -141,6 +142,7 @@ 
 	{ EXIT_REASON_ENCLS,                 "ENCLS" }, \
 	{ EXIT_REASON_RDSEED,                "RDSEED" }, \
 	{ EXIT_REASON_PML_FULL,              "PML_FULL" }, \
+	{ EXIT_REASON_SPP,                   "SPP" }, \
 	{ EXIT_REASON_XSAVES,                "XSAVES" }, \
 	{ EXIT_REASON_XRSTORS,               "XRSTORS" }
 
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 38e79210d010..d59108a3ebbf 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3692,6 +3692,19 @@  static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
 		if ((error_code & PFERR_WRITE_MASK) &&
 		    spte_can_locklessly_be_made_writable(spte))
 		{
+			/*
+			 * Record write protect fault caused by
+			 * Sub-page Protection, let VMI decide
+			 * the next step.
+			 */
+			if (spte & PT_SPP_MASK) {
+				fault_handled = true;
+				vcpu->run->exit_reason = KVM_EXIT_SPP;
+				vcpu->run->spp.addr = gva;
+				kvm_skip_emulated_instruction(vcpu);
+				break;
+			}
+
 			new_spte |= PT_WRITABLE_MASK;
 
 			/*
@@ -5880,6 +5893,10 @@  int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,
 		r = vcpu->arch.mmu->page_fault(vcpu, cr2,
 					       lower_32_bits(error_code),
 					       false);
+
+		if (vcpu->run->exit_reason == KVM_EXIT_SPP)
+			return 0;
+
 		WARN_ON(r == RET_PF_INVALID);
 	}
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index a50dd2b9d438..5d4b61aaff9a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5335,6 +5335,76 @@  static int handle_monitor(struct kvm_vcpu *vcpu)
 	return handle_nop(vcpu);
 }
 
+static int handle_spp(struct kvm_vcpu *vcpu)
+{
+	unsigned long exit_qualification;
+	struct kvm_memory_slot *slot;
+	gpa_t gpa;
+	gfn_t gfn;
+
+	exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
+
+	/*
+	 * SPP VM exit happened while executing iret from NMI,
+	 * "blocked by NMI" bit has to be set before next VM entry.
+	 * There are errata that may cause this bit to not be set:
+	 * AAK134, BY25.
+	 */
+	if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
+	    (exit_qualification & SPPT_INTR_INFO_UNBLOCK_NMI))
+		vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
+			      GUEST_INTR_STATE_NMI);
+
+	vcpu->arch.exit_qualification = exit_qualification;
+	if (exit_qualification & SPPT_INDUCED_EXIT_TYPE) {
+		struct kvm_subpage spp_info = {0};
+		int ret;
+
+		/*
+		 * SPPT missing
+		 * We don't set SPP write access for the corresponding
+		 * GPA, if we haven't setup, we need to construct
+		 * SPP table here.
+		 */
+		pr_info("SPP - SPPT entry missing!\n");
+		gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
+		gfn = gpa >> PAGE_SHIFT;
+		slot = gfn_to_memslot(vcpu->kvm, gfn);
+		if (!slot)
+		      return -EFAULT;
+
+		/*
+		 * if the target gfn is not protected, but SPPT is
+		 * traversed now, regard this as some kind of fault.
+		 */
+		spp_info.base_gfn = gfn;
+		spp_info.npages = 1;
+
+		spin_lock(&(vcpu->kvm->mmu_lock));
+		ret = kvm_mmu_get_subpages(vcpu->kvm, &spp_info, true);
+		if (ret == 1) {
+			kvm_mmu_setup_spp_structure(vcpu,
+				spp_info.access_map[0], gfn);
+		}
+		spin_unlock(&(vcpu->kvm->mmu_lock));
+
+		return 1;
+
+	}
+
+	/*
+	 * SPPT Misconfig
+	 * This is probably caused by some mis-configuration in SPPT
+	 * entries, cannot handle it here, escalate the fault to
+	 * emulator.
+	 */
+	WARN_ON(1);
+	vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
+	vcpu->run->hw.hardware_exit_reason = EXIT_REASON_SPP;
+	pr_alert("SPP - SPPT Misconfiguration!\n");
+	return 0;
+}
+
 static int handle_invpcid(struct kvm_vcpu *vcpu)
 {
 	u32 vmx_instruction_info;
@@ -5538,6 +5608,7 @@  static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_INVVPID]                 = handle_vmx_instruction,
 	[EXIT_REASON_RDRAND]                  = handle_invalid_op,
 	[EXIT_REASON_RDSEED]                  = handle_invalid_op,
+	[EXIT_REASON_SPP]                     = handle_spp,
 	[EXIT_REASON_XSAVES]                  = handle_xsaves,
 	[EXIT_REASON_XRSTORS]                 = handle_xrstors,
 	[EXIT_REASON_PML_FULL]		      = handle_pml_full,
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 86dd57e67539..81f08eec9061 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -244,6 +244,7 @@  struct kvm_hyperv_exit {
 #define KVM_EXIT_S390_STSI        25
 #define KVM_EXIT_IOAPIC_EOI       26
 #define KVM_EXIT_HYPERV           27
+#define KVM_EXIT_SPP              28
 
 /* For KVM_EXIT_INTERNAL_ERROR */
 /* Emulate instruction failed. */
@@ -399,6 +400,10 @@  struct kvm_run {
 		struct {
 			__u8 vector;
 		} eoi;
+		/* KVM_EXIT_SPP */
+		struct {
+			__u64 addr;
+		} spp;
 		/* KVM_EXIT_HYPERV */
 		struct kvm_hyperv_exit hyperv;
 		/* Fix the size of the union. */