Confidential guest live migration

[RFC PATCH 23/26] target/i386: Re-sync kvm-clock after confidential guest migration

Dov Murik posted 26 patches 4 years, 11 months ago

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Maintainers: "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Eric Blake <eblake@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Markus Armbruster <armbru@redhat.com>, Juan Quintela <quintela@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>

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[RFC PATCH 23/26] target/i386: Re-sync kvm-clock after confidential guest migration

Posted by Dov Murik 4 years, 11 months ago

If confidential guest support is active, set TSC to 0 on the target when
loading the CPU state.  This causes the guest OS to re-sync with
kvm-clock.

Without this change, the guest clocks after migration are stuck (don't
advance), except the *_COARSE clocks which advance normally.

Signed-off-by: Dov Murik <dovmurik@linux.vnet.ibm.com>
---
 target/i386/machine.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/target/i386/machine.c b/target/i386/machine.c
index 3768a753af..36c52ec02e 100644
--- a/target/i386/machine.c
+++ b/target/i386/machine.c
@@ -297,8 +297,17 @@ static int cpu_post_load(void *opaque, int version_id)
     X86CPU *cpu = opaque;
     CPUState *cs = CPU(cpu);
     CPUX86State *env = &cpu->env;
+    MachineState *ms = MACHINE(qdev_get_machine());
     int i;
 
+    /*
+     * When loading the state of a confidential guest, set TSC to zero at allow
+     * the guest OS to re-sync with kvmclock.
+     */
+    if (ms->cgs) {
+        env->tsc = 0;
+    }
+
     if (env->tsc_khz && env->user_tsc_khz &&
         env->tsc_khz != env->user_tsc_khz) {
         error_report("Mismatch between user-specified TSC frequency and "
-- 
2.20.1