[PULL 0/1] x86 bug fix for -rc2

[PULL 0/1] x86 bug fix for -rc2

[Eduardo Habkost]

The following changes since commit 8ffa52c20d5693d454f65f2024a1494edfea65d4:

  Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging (2020-07-23 13:38:21 +0100)

are available in the Git repository at:

  git://github.com/ehabkost/qemu.git tags/x86-next-for-5.1-pull-request

for you to fetch changes up to 0baa4b445e28f37243e5dc72e7efe32f0c9d7801:

  KVM: fix CPU reset wrt HF2_GIF_MASK (2020-07-23 15:03:54 -0400)

----------------------------------------------------------------
x86 bug fix for -rc2

A fix from Vitaly Kuznetsov for a CPU reset bug
reported by Jan Kiszka.

----------------------------------------------------------------

Vitaly Kuznetsov (1):
  KVM: fix CPU reset wrt HF2_GIF_MASK

 target/i386/kvm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

-- 
2.26.2

[PULL 1/1] KVM: fix CPU reset wrt HF2_GIF_MASK

[Eduardo Habkost]

From: Vitaly Kuznetsov <vkuznets@redhat.com>

HF2_GIF_MASK is set in env->hflags2 unconditionally on CPU reset
(see x86_cpu_reset()) but when calling KVM_SET_NESTED_STATE,
KVM_STATE_NESTED_GIF_SET is only valid for nSVM as e.g. nVMX code
looks like

if (kvm_state->hdr.vmx.vmxon_pa == -1ull) {
    if (kvm_state->flags & ~KVM_STATE_NESTED_EVMCS)
        return -EINVAL;
}

Also, when adjusting the environment after KVM_GET_NESTED_STATE we
need not reset HF2_GIF_MASK on VMX as e.g. x86_cpu_pending_interrupt()
expects it to be set.

Alternatively, we could've made env->hflags2 SVM-only.

Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Fixes: b16c0e20c742 ("KVM: add support for AMD nested live migration")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200723142701.2521161-1-vkuznets@redhat.com>
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/kvm.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index b8455c89ed..6f18d940a5 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -3877,7 +3877,9 @@ static int kvm_put_nested_state(X86CPU *cpu)
     } else {
         env->nested_state->flags &= ~KVM_STATE_NESTED_GUEST_MODE;
     }
-    if (env->hflags2 & HF2_GIF_MASK) {
+
+    /* Don't set KVM_STATE_NESTED_GIF_SET on VMX as it is illegal */
+    if (cpu_has_svm(env) && (env->hflags2 & HF2_GIF_MASK)) {
         env->nested_state->flags |= KVM_STATE_NESTED_GIF_SET;
     } else {
         env->nested_state->flags &= ~KVM_STATE_NESTED_GIF_SET;
@@ -3919,10 +3921,14 @@ static int kvm_get_nested_state(X86CPU *cpu)
     } else {
         env->hflags &= ~HF_GUEST_MASK;
     }
-    if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) {
-        env->hflags2 |= HF2_GIF_MASK;
-    } else {
-        env->hflags2 &= ~HF2_GIF_MASK;
+
+    /* Keep HF2_GIF_MASK set on !SVM as x86_cpu_pending_interrupt() needs it */
+    if (cpu_has_svm(env)) {
+        if (env->nested_state->flags & KVM_STATE_NESTED_GIF_SET) {
+            env->hflags2 |= HF2_GIF_MASK;
+        } else {
+            env->hflags2 &= ~HF2_GIF_MASK;
+        }
     }
 
     return ret;
-- 
2.26.2

Re: [PULL 0/1] x86 bug fix for -rc2

[Peter Maydell]

On Thu, 23 Jul 2020 at 20:14, Eduardo Habkost <ehabkost@redhat.com> wrote:
>
> The following changes since commit 8ffa52c20d5693d454f65f2024a1494edfea65d4:
>
>   Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging (2020-07-23 13:38:21 +0100)
>
> are available in the Git repository at:
>
>   git://github.com/ehabkost/qemu.git tags/x86-next-for-5.1-pull-request
>
> for you to fetch changes up to 0baa4b445e28f37243e5dc72e7efe32f0c9d7801:
>
>   KVM: fix CPU reset wrt HF2_GIF_MASK (2020-07-23 15:03:54 -0400)
>
> ----------------------------------------------------------------
> x86 bug fix for -rc2
>
> A fix from Vitaly Kuznetsov for a CPU reset bug
> reported by Jan Kiszka.
>
> ----------------------------------------------------------------


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/5.1
for any user-visible changes.

-- PMM