Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "s390:
   - optimization for the exitless interrupt support that was merged in 4.16-rc1
   - improve the branch prediction blocking for nested KVM
   - replace some jump tables with switch statements to improve expoline performance
   - fixes for multiple epoch facility

  ARM:
   - fix the interaction of userspace irqchip VMs with in-kernel irqchip VMs
   - make sure we can build 32-bit KVM/ARM with gcc-8.

  x86:
   - fixes for AMD SEV
   - fixes for Intel nested VMX, emulated UMIP and a dump_stack() on VM startup
   - fixes for async page fault migration
   - small optimization to PV TLB flush (new in 4.16-rc1)
   - syzkaller fixes

  Generic:
   - compiler warning fixes
   - syzkaller fixes
   - more improvements to the kvm_stat tool

  Two more small Spectre fixes are going to reach you via Ingo"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (40 commits)
  KVM: SVM: Fix SEV LAUNCH_SECRET command
  KVM: SVM: install RSM intercept
  KVM: SVM: no need to call access_ok() in LAUNCH_MEASURE command
  include: psp-sev: Capitalize invalid length enum
  crypto: ccp: Fix sparse, use plain integer as NULL pointer
  KVM: X86: Avoid traversing all the cpus for pv tlb flush when steal time is disabled
  x86/kvm: Make parse_no_xxx __init for kvm
  KVM: x86: fix backward migration with async_PF
  kvm: fix warning for non-x86 builds
  kvm: fix warning for CONFIG_HAVE_KVM_EVENTFD builds
  tools/kvm_stat: print 'Total' line for multiple events only
  tools/kvm_stat: group child events indented after parent
  tools/kvm_stat: separate drilldown and fields filtering
  tools/kvm_stat: eliminate extra guest/pid selection dialog
  tools/kvm_stat: mark private methods as such
  tools/kvm_stat: fix debugfs handling
  tools/kvm_stat: print error on invalid regex
  tools/kvm_stat: fix crash when filtering out all non-child trace events
  tools/kvm_stat: avoid 'is' for equality checks
  tools/kvm_stat: use a more pythonic way to iterate over dictionaries
  ...

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index ec772700ff96..8961e3970901 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -821,6 +821,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 {
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
 	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
+	int guest_bp_isolation;
 	int rc;
 
 	handle_last_fault(vcpu, vsie_page);
@@ -831,6 +832,20 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		s390_handle_mcck();
 
 	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+
+	/* save current guest state of bp isolation override */
+	guest_bp_isolation = test_thread_flag(TIF_ISOLATE_BP_GUEST);
+
+	/*
+	 * The guest is running with BPBC, so we have to force it on for our
+	 * nested guest. This is done by enabling BPBC globally, so the BPBC
+	 * control in the SCB (which the nested guest can modify) is simply
+	 * ignored.
+	 */
+	if (test_kvm_facility(vcpu->kvm, 82) &&
+	    vcpu->arch.sie_block->fpf & FPF_BPBC)
+		set_thread_flag(TIF_ISOLATE_BP_GUEST);
+
 	local_irq_disable();
 	guest_enter_irqoff();
 	local_irq_enable();
@@ -840,6 +855,11 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	local_irq_disable();
 	guest_exit_irqoff();
 	local_irq_enable();
+
+	/* restore guest state for bp isolation override */
+	if (!guest_bp_isolation)
+		clear_thread_flag(TIF_ISOLATE_BP_GUEST);
+
 	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 	if (rc == -EINTR) {