Patchwork [V3] target-i386: Enabling IA32_TSC_ADJUST for QEMU KVM guest VMs

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Submitter Will Auld
Date Nov. 27, 2012, 1:40 a.m.
Message ID <1353980434.8358.2.camel@WillAuldHomeLinux>
Download mbox | patch
Permalink /patch/202065/
State New
Headers show

Comments

Will Auld - Nov. 27, 2012, 1:40 a.m.
CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported

Basic design is to emulate the MSR by allowing reads and writes to the
hypervisor vcpu specific locations to store the value of the emulated MSRs.
In this way the IA32_TSC_ADJUST value will be included in all reads to
the TSC MSR whether through rdmsr or rdtsc.

As this is a new MSR that the guest may access and modify its value needs
to be migrated along with the other MRSs. The changes here are specifically
for recognizing when IA32_TSC_ADJUST is enabled in CPUID and code added
for migrating its value.

Signed-off-by: Will Auld <will.auld@intel.com>
---
 target-i386/cpu.h     |  2 ++
 target-i386/kvm.c     | 15 +++++++++++++++
 target-i386/machine.c | 21 +++++++++++++++++++++
 3 files changed, 38 insertions(+)
Andreas Färber - Nov. 27, 2012, 1:51 a.m.
Am 27.11.2012 02:40, schrieb Will Auld:
> CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported
> 
> Basic design is to emulate the MSR by allowing reads and writes to the
> hypervisor vcpu specific locations to store the value of the emulated MSRs.
> In this way the IA32_TSC_ADJUST value will be included in all reads to
> the TSC MSR whether through rdmsr or rdtsc.
> 
> As this is a new MSR that the guest may access and modify its value needs
> to be migrated along with the other MRSs. The changes here are specifically
> for recognizing when IA32_TSC_ADJUST is enabled in CPUID and code added
> for migrating its value.
> 
> Signed-off-by: Will Auld <will.auld@intel.com>

Something went wrong here, none of the V2 review comments are addressed.
Maybe you sent the wrong patch file?

Cheers,
Andreas
Auld, Will - Nov. 27, 2012, 1:56 a.m.
Sorry, let me figure this out and resend.

Thanks,

Will

> -----Original Message-----

> From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On

> Behalf Of Andreas Färber

> Sent: Monday, November 26, 2012 5:51 PM

> To: Auld, Will

> Cc: Will Auld; qemu-devel; Gleb; mtosatti@redhat.com;

> kvm@vger.kernel.org; Dugger, Donald D; Liu, Jinsong; Zhang, Xiantao;

> avi@redhat.com

> Subject: Re: [Qemu-devel] [PATCH V3] target-i386: Enabling

> IA32_TSC_ADJUST for QEMU KVM guest VMs

> 

> Am 27.11.2012 02:40, schrieb Will Auld:

> > CPUID.7.0.EBX[1]=1 indicates IA32_TSC_ADJUST MSR 0x3b is supported

> >

> > Basic design is to emulate the MSR by allowing reads and writes to

> the

> > hypervisor vcpu specific locations to store the value of the emulated

> MSRs.

> > In this way the IA32_TSC_ADJUST value will be included in all reads

> to

> > the TSC MSR whether through rdmsr or rdtsc.

> >

> > As this is a new MSR that the guest may access and modify its value

> > needs to be migrated along with the other MRSs. The changes here are

> > specifically for recognizing when IA32_TSC_ADJUST is enabled in CPUID

> > and code added for migrating its value.

> >

> > Signed-off-by: Will Auld <will.auld@intel.com>

> 

> Something went wrong here, none of the V2 review comments are

> addressed.

> Maybe you sent the wrong patch file?

> 

> Cheers,

> Andreas

> 

> --

> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany

> GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

> --

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Patch

diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index aabf993..13d4152 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -284,6 +284,7 @@ 
 #define MSR_IA32_APICBASE_BSP           (1<<8)
 #define MSR_IA32_APICBASE_ENABLE        (1<<11)
 #define MSR_IA32_APICBASE_BASE          (0xfffff<<12)
+#define MSR_TSC_ADJUST	 		0x0000003b
 #define MSR_IA32_TSCDEADLINE            0x6e0
 
 #define MSR_MTRRcap			0xfe
@@ -701,6 +702,7 @@  typedef struct CPUX86State {
     uint64_t async_pf_en_msr;
 
     uint64_t tsc;
+    uint64_t tsc_adjust;
     uint64_t tsc_deadline;
 
     uint64_t mcg_status;
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 696b14a..e974c42 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -61,6 +61,7 @@  const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
 
 static bool has_msr_star;
 static bool has_msr_hsave_pa;
+static bool has_msr_tsc_adjust;
 static bool has_msr_tsc_deadline;
 static bool has_msr_async_pf_en;
 static bool has_msr_misc_enable;
@@ -641,6 +642,10 @@  static int kvm_get_supported_msrs(KVMState *s)
                     has_msr_hsave_pa = true;
                     continue;
                 }
+                if (kvm_msr_list->indices[i] == MSR_TSC_ADJUST) {
+                    has_msr_tsc_adjust = true;
+                    continue;
+                }
                 if (kvm_msr_list->indices[i] == MSR_IA32_TSCDEADLINE) {
                     has_msr_tsc_deadline = true;
                     continue;
@@ -978,6 +983,10 @@  static int kvm_put_msrs(CPUX86State *env, int level)
     if (has_msr_hsave_pa) {
         kvm_msr_entry_set(&msrs[n++], MSR_VM_HSAVE_PA, env->vm_hsave);
     }
+    if (has_msr_tsc_adjust) {
+        kvm_msr_entry_set(&msrs[n++], 
+			MSR_TSC_ADJUST, env->tsc_adjust);
+    }
     if (has_msr_tsc_deadline) {
         kvm_msr_entry_set(&msrs[n++], MSR_IA32_TSCDEADLINE, env->tsc_deadline);
     }
@@ -1234,6 +1243,9 @@  static int kvm_get_msrs(CPUX86State *env)
     if (has_msr_hsave_pa) {
         msrs[n++].index = MSR_VM_HSAVE_PA;
     }
+    if (has_msr_tsc_adjust) {
+        msrs[n++].index = MSR_TSC_ADJUST;
+    }
     if (has_msr_tsc_deadline) {
         msrs[n++].index = MSR_IA32_TSCDEADLINE;
     }
@@ -1308,6 +1320,9 @@  static int kvm_get_msrs(CPUX86State *env)
         case MSR_IA32_TSC:
             env->tsc = msrs[i].data;
             break;
+        case MSR_TSC_ADJUST:
+            env->tsc_adjust = msrs[i].data;
+            break;
         case MSR_IA32_TSCDEADLINE:
             env->tsc_deadline = msrs[i].data;
             break;
diff --git a/target-i386/machine.c b/target-i386/machine.c
index a8be058..95bda9b 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -310,6 +310,24 @@  static const VMStateDescription vmstate_fpop_ip_dp = {
     }
 };
 
+static bool tsc_adjust_needed(void *opaque)
+{
+    CPUX86State *cpu = opaque;
+
+    return cpu->tsc_adjust != 0;
+}
+
+static const VMStateDescription vmstate_msr_tsc_adjust = {
+    .name = "cpu/msr_tsc_adjust",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField []) {
+        VMSTATE_UINT64(tsc_adjust, CPUX86State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static bool tscdeadline_needed(void *opaque)
 {
     CPUX86State *env = opaque;
@@ -457,6 +475,9 @@  static const VMStateDescription vmstate_cpu = {
             .vmsd = &vmstate_fpop_ip_dp,
             .needed = fpop_ip_dp_needed,
         }, {
+            .vmsd = &vmstate_msr_tsc_adjust,
+            .needed = tsc_adjust_needed,
+        }, {
             .vmsd = &vmstate_msr_tscdeadline,
             .needed = tscdeadline_needed,
         }, {