From d72e41f9a16360eb23e9d943fa7e33291c5fcd87 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 17 Feb 2020 16:23:18 -0500
Subject: [PATCH 03/12] target/i386: kvm: initialize feature MSRs very early
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RH-Author: Paolo Bonzini <pbonzini@redhat.com>
Message-id: <20200217162323.2572-2-pbonzini@redhat.com>
Patchwork-id: 93896
O-Subject: [RHEL7.9 qemu-kvm-rhev PATCH 1/6] target/i386: kvm: initialize feature MSRs very early
Bugzilla: 1791653
RH-Acked-by: Maxim Levitsky <mlevitsk@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Some read-only MSRs affect the behavior of ioctls such as
KVM_SET_NESTED_STATE.  We can initialize them once and for all
right after the CPU is realized, since they will never be modified
by the guest.

Reported-by: Qingua Cheng <qcheng@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1579544504-3616-2-git-send-email-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 420ae1fc51c99abfd03b1c590f55617edd2a2bed)

[RHEL7: no MSR_IA32_CORE_CAPABILITY]

Signed-off-by: Jon Maloy <jmaloy.redhat.com>
---
 target/i386/kvm.c      | 55 +++++++++++++++++++++++++++---------------
 target/i386/kvm_i386.h |  1 +
 2 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index a6e5a87cf5..d8a4dbfde3 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -65,6 +65,8 @@
  * 255 kvm_msr_entry structs */
 #define MSR_BUF_SIZE 4096
 
+static void kvm_init_msrs(X86CPU *cpu);
+
 const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
     KVM_CAP_INFO(SET_TSS_ADDR),
     KVM_CAP_INFO(EXT_CPUID),
@@ -1175,6 +1177,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
         has_msr_tsc_aux = false;
     }
 
+    kvm_init_msrs(cpu);
+
     return 0;
 
  fail:
@@ -1797,11 +1801,40 @@ static int kvm_put_msr_feature_control(X86CPU *cpu)
     return 0;
 }
 
+static int kvm_buf_set_msrs(X86CPU *cpu)
+{
+    int ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, cpu->kvm_msr_buf);
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (ret < cpu->kvm_msr_buf->nmsrs) {
+        struct kvm_msr_entry *e = &cpu->kvm_msr_buf->entries[ret];
+        error_report("error: failed to set MSR 0x%" PRIx32 " to 0x%" PRIx64,
+                     (uint32_t)e->index, (uint64_t)e->data);
+    }
+
+    assert(ret == cpu->kvm_msr_buf->nmsrs);
+    return 0;
+}
+
+static void kvm_init_msrs(X86CPU *cpu)
+{
+    CPUX86State *env = &cpu->env;
+
+    kvm_msr_buf_reset(cpu);
+    if (has_msr_arch_capabs) {
+        kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
+                          env->features[FEAT_ARCH_CAPABILITIES]);
+    }
+
+    assert(kvm_buf_set_msrs(cpu) == 0);
+}
+
 static int kvm_put_msrs(X86CPU *cpu, int level)
 {
     CPUX86State *env = &cpu->env;
     int i;
-    int ret;
 
     kvm_msr_buf_reset(cpu);
 
@@ -1856,12 +1889,6 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
     }
 #endif
 
-    /* If host supports feature MSR, write down. */
-    if (has_msr_arch_capabs) {
-        kvm_msr_entry_add(cpu, MSR_IA32_ARCH_CAPABILITIES,
-                          env->features[FEAT_ARCH_CAPABILITIES]);
-    }
-
     /*
      * The following MSRs have side effects on the guest or are too heavy
      * for normal writeback. Limit them to reset or full state updates.
@@ -2040,19 +2067,7 @@ static int kvm_put_msrs(X86CPU *cpu, int level)
         }
     }
 
-    ret = kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, cpu->kvm_msr_buf);
-    if (ret < 0) {
-        return ret;
-    }
-
-    if (ret < cpu->kvm_msr_buf->nmsrs) {
-        struct kvm_msr_entry *e = &cpu->kvm_msr_buf->entries[ret];
-        error_report("error: failed to set MSR 0x%" PRIx32 " to 0x%" PRIx64,
-                     (uint32_t)e->index, (uint64_t)e->data);
-    }
-
-    assert(ret == cpu->kvm_msr_buf->nmsrs);
-    return 0;
+    return kvm_buf_set_msrs(cpu);
 }
 
 
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 1de9876cd9..856044750e 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -69,4 +69,5 @@ void kvm_put_apicbase(X86CPU *cpu, uint64_t value);
 
 bool kvm_enable_x2apic(void);
 bool kvm_has_x2apic_api(void);
+
 #endif
-- 
2.18.2