Merge tag 'kvm-s390-master-5.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-master

KVM: s390: Fix for 5.7 and maintainer update

- Silence false positive lockdep warning
- add Claudio as reviewer

3 files changed, 45 insertions, 8 deletions

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 9fea0757db92..d8154e0684b6 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -107,8 +107,4 @@ config KVM_MMU_AUDIT
 	 This option adds a R/W kVM module parameter 'mmu_audit', which allows
 	 auditing of KVM MMU events at runtime.
 
-# OK, it's a little counter-intuitive to do this, but it puts it neatly under
-# the virtualization menu.
-source "drivers/vhost/Kconfig"
-
 endif # VIRTUALIZATION
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 01330096ff3e..c2c6335a998c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4588,6 +4588,26 @@ static int handle_machine_check(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+/*
+ * If the host has split lock detection disabled, then #AC is
+ * unconditionally injected into the guest, which is the pre split lock
+ * detection behaviour.
+ *
+ * If the host has split lock detection enabled then #AC is
+ * only injected into the guest when:
+ *  - Guest CPL == 3 (user mode)
+ *  - Guest has #AC detection enabled in CR0
+ *  - Guest EFLAGS has AC bit set
+ */
+static inline bool guest_inject_ac(struct kvm_vcpu *vcpu)
+{
+	if (!boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
+		return true;
+
+	return vmx_get_cpl(vcpu) == 3 && kvm_read_cr0_bits(vcpu, X86_CR0_AM) &&
+	       (kvm_get_rflags(vcpu) & X86_EFLAGS_AC);
+}
+
 static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -4653,9 +4673,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 		return handle_rmode_exception(vcpu, ex_no, error_code);
 
 	switch (ex_no) {
-	case AC_VECTOR:
-		kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
-		return 1;
 	case DB_VECTOR:
 		dr6 = vmcs_readl(EXIT_QUALIFICATION);
 		if (!(vcpu->guest_debug &
@@ -4684,6 +4701,20 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
 		kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
 		kvm_run->debug.arch.exception = ex_no;
 		break;
+	case AC_VECTOR:
+		if (guest_inject_ac(vcpu)) {
+			kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
+			return 1;
+		}
+
+		/*
+		 * Handle split lock. Depending on detection mode this will
+		 * either warn and disable split lock detection for this
+		 * task or force SIGBUS on it.
+		 */
+		if (handle_guest_split_lock(kvm_rip_read(vcpu)))
+			return 1;
+		fallthrough;
 	default:
 		kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
 		kvm_run->ex.exception = ex_no;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 919d3c8f9b65..c5835f9cb9ad 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5856,6 +5856,7 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 {
 	struct kvm_host_map map;
 	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
+	u64 page_line_mask;
 	gpa_t gpa;
 	char *kaddr;
 	bool exchanged;
@@ -5870,7 +5871,16 @@ static int emulator_cmpxchg_emulated(struct x86_emulate_ctxt *ctxt,
 	    (gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
 		goto emul_write;
 
-	if (((gpa + bytes - 1) & PAGE_MASK) != (gpa & PAGE_MASK))
+	/*
+	 * Emulate the atomic as a straight write to avoid #AC if SLD is
+	 * enabled in the host and the access splits a cache line.
+	 */
+	if (boot_cpu_has(X86_FEATURE_SPLIT_LOCK_DETECT))
+		page_line_mask = ~(cache_line_size() - 1);
+	else
+		page_line_mask = PAGE_MASK;
+
+	if (((gpa + bytes - 1) & page_line_mask) != (gpa & page_line_mask))
 		goto emul_write;
 
 	if (kvm_vcpu_map(vcpu, gpa_to_gfn(gpa), &map))