4.4-stable patches

added patches:
	x86-kvm-vmx-do-not-use-vm-exit-instruction-length-for-fast-mmio-when-running-nested.patch

diff --git a/queue-4.4/series b/queue-4.4/series
index 0b84735130371665132358a10907ec746cf25319..2fd11fa5c76b5710ce5a82debbaabe3fa3ca86da 100644 (file)
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -53,3 +53,4 @@ media-vivid-free-bitmap_cap-when-updating-std-timings-etc.patch
 mips-ensure-pmd_present-returns-false-after-pmd_mknotpresent.patch
 mips-align-kernel-load-address-to-64kb.patch
 cifs-fix-error-mapping-for-smb2_lock-command-which-caused-ofd-lock-problem.patch
+x86-kvm-vmx-do-not-use-vm-exit-instruction-length-for-fast-mmio-when-running-nested.patch

diff --git a/queue-4.4/x86-kvm-vmx-do-not-use-vm-exit-instruction-length-for-fast-mmio-when-running-nested.patch b/queue-4.4/x86-kvm-vmx-do-not-use-vm-exit-instruction-length-for-fast-mmio-when-running-nested.patch
new file mode 100644 (file)
index 0000000..67370f1
--- /dev/null
+++ b/queue-4.4/x86-kvm-vmx-do-not-use-vm-exit-instruction-length-for-fast-mmio-when-running-nested.patch
@@ -0,0 +1,86 @@
+From d391f1207067268261add0485f0f34503539c5b0 Mon Sep 17 00:00:00 2001
+From: Vitaly Kuznetsov <vkuznets@redhat.com>
+Date: Thu, 25 Jan 2018 16:37:07 +0100
+Subject: x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO when running nested
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Vitaly Kuznetsov <vkuznets@redhat.com>
+
+commit d391f1207067268261add0485f0f34503539c5b0 upstream.
+
+I was investigating an issue with seabios >= 1.10 which stopped working
+for nested KVM on Hyper-V. The problem appears to be in
+handle_ept_violation() function: when we do fast mmio we need to skip
+the instruction so we do kvm_skip_emulated_instruction(). This, however,
+depends on VM_EXIT_INSTRUCTION_LEN field being set correctly in VMCS.
+However, this is not the case.
+
+Intel's manual doesn't mandate VM_EXIT_INSTRUCTION_LEN to be set when
+EPT MISCONFIG occurs. While on real hardware it was observed to be set,
+some hypervisors follow the spec and don't set it; we end up advancing
+IP with some random value.
+
+I checked with Microsoft and they confirmed they don't fill
+VM_EXIT_INSTRUCTION_LEN on EPT MISCONFIG.
+
+Fix the issue by doing instruction skip through emulator when running
+nested.
+
+Fixes: 68c3b4d1676d870f0453c31d5a52e7e65c7448ae
+Suggested-by: Radim Krčmář <rkrcmar@redhat.com>
+Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
+Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
+Acked-by: Michael S. Tsirkin <mst@redhat.com>
+Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
+Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
+[mhaboustak: backport to 4.9.y]
+Signed-off-by: Mike Haboustak <haboustak@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/kvm/vmx.c |   19 +++++++++++++++++--
+ arch/x86/kvm/x86.c |    3 ++-
+ 2 files changed, 19 insertions(+), 3 deletions(-)
+
+--- a/arch/x86/kvm/vmx.c
++++ b/arch/x86/kvm/vmx.c
+@@ -6163,9 +6163,24 @@ static int handle_ept_misconfig(struct k
+ 
+       gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
+       if (!kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) {
+-              skip_emulated_instruction(vcpu);
+               trace_kvm_fast_mmio(gpa);
+-              return 1;
++              /*
++              * Doing kvm_skip_emulated_instruction() depends on undefined
++              * behavior: Intel's manual doesn't mandate
++              * VM_EXIT_INSTRUCTION_LEN to be set in VMCS when EPT MISCONFIG
++              * occurs and while on real hardware it was observed to be set,
++              * other hypervisors (namely Hyper-V) don't set it, we end up
++              * advancing IP with some random value. Disable fast mmio when
++              * running nested and keep it for real hardware in hope that
++              * VM_EXIT_INSTRUCTION_LEN will always be set correctly.
++              */
++              if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) {
++                      skip_emulated_instruction(vcpu);
++                      return 1;
++              }
++              else
++                      return x86_emulate_instruction(vcpu, gpa, EMULTYPE_SKIP,
++                                                     NULL, 0) == EMULATE_DONE;
+       }
+ 
+       ret = handle_mmio_page_fault(vcpu, gpa, true);
+--- a/arch/x86/kvm/x86.c
++++ b/arch/x86/kvm/x86.c
+@@ -5436,7 +5436,8 @@ int x86_emulate_instruction(struct kvm_v
+                * handle watchpoints yet, those would be handled in
+                * the emulate_ops.
+                */
+-              if (kvm_vcpu_check_breakpoint(vcpu, &r))
++              if (!(emulation_type & EMULTYPE_SKIP) &&
++                  kvm_vcpu_check_breakpoint(vcpu, &r))
+                       return r;
+ 
+               ctxt->interruptibility = 0;