Enabling Hyper-V emulation for a Windows VM is a tiring experience as it
requires listing all currently supported enlightenments ("hv-*" CPU
features) explicitly. We do have 'hv-passthrough' mode enabling
everything but it can't be used in production as it prevents migration.
Introduce a simple 'hv-default=on' CPU flag enabling all currently supported
Hyper-V enlightenments. Later, when new enlightenments get implemented,
compat_props mechanism will be used to disable them for legacy machine types,
this will keep 'hv-default=on' configurations migratable.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
docs/hyperv.txt | 16 ++++++++++++---
target/i386/cpu.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
target/i386/cpu.h | 3 +++
3 files changed, 68 insertions(+), 3 deletions(-)
diff --git a/docs/hyperv.txt b/docs/hyperv.txt
index 5df00da54fc4..a54c066cab09 100644
--- a/docs/hyperv.txt
+++ b/docs/hyperv.txt
@@ -17,10 +17,20 @@ compatible hypervisor and use Hyper-V specific features.
2. Setup
=========
-No Hyper-V enlightenments are enabled by default by either KVM or QEMU. In
-QEMU, individual enlightenments can be enabled through CPU flags, e.g:
+All currently supported Hyper-V enlightenments can be enabled by specifying
+'hv-default=on' CPU flag:
- qemu-system-x86_64 --enable-kvm --cpu host,hv_relaxed,hv_vpindex,hv_time, ...
+ qemu-system-x86_64 --enable-kvm --cpu host,hv-default ...
+
+Alternatively, it is possible to do fine-grained enablement through CPU flags,
+e.g:
+
+ qemu-system-x86_64 --enable-kvm --cpu host,hv-relaxed,hv-vpindex,hv-time ...
+
+It is also possible to disable individual enlightenments from the default list,
+this can be used for debugging purposes:
+
+ qemu-system-x86_64 --enable-kvm --cpu host,hv-default=on,hv-evmcs=off ...
Sometimes there are dependencies between enlightenments, QEMU is supposed to
check that the supplied configuration is sane.
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index f8df2caed779..013aa60272d8 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4736,6 +4736,12 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
{
X86CPU *cpu = X86_CPU(obj);
+ if (cpu->hyperv_default) {
+ error_setg(errp,
+ "'hv-default' and 'hv-paththrough' are mutually exclusive");
+ return;
+ }
+
cpu->hyperv_passthrough = value;
/* hv-passthrough overrides everything with what's supported by the host */
@@ -4748,6 +4754,33 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
return;
}
+static bool x86_hv_default_get(Object *obj, Error **errp)
+{
+ X86CPU *cpu = X86_CPU(obj);
+
+ return cpu->hyperv_default;
+}
+
+static void x86_hv_default_set(Object *obj, bool value, Error **errp)
+{
+ X86CPU *cpu = X86_CPU(obj);
+
+ if (cpu->hyperv_passthrough) {
+ error_setg(errp,
+ "'hv-default' and 'hv-paththrough' are mutually exclusive");
+ return;
+ }
+
+ cpu->hyperv_default = value;
+
+ /* hv-default overrides everything with the default set */
+ if (value) {
+ cpu->hyperv_features = cpu->hyperv_default_features;
+ cpu->hyperv_features_on = 0;
+ cpu->hyperv_features_off = 0;
+ }
+}
+
/* Generic getter for "feature-words" and "filtered-features" properties */
static void x86_cpu_get_feature_words(Object *obj, Visitor *v,
const char *name, void *opaque,
@@ -7152,6 +7185,21 @@ static void x86_cpu_initfn(Object *obj)
if (xcc->model) {
x86_cpu_load_model(cpu, xcc->model);
}
+
+ /* Hyper-V features enabled with 'hv-default=on' */
+ cpu->hyperv_default_features = BIT(HYPERV_FEAT_RELAXED) |
+ BIT(HYPERV_FEAT_VAPIC) | BIT(HYPERV_FEAT_TIME) |
+ BIT(HYPERV_FEAT_CRASH) | BIT(HYPERV_FEAT_RESET) |
+ BIT(HYPERV_FEAT_VPINDEX) | BIT(HYPERV_FEAT_RUNTIME) |
+ BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_STIMER) |
+ BIT(HYPERV_FEAT_FREQUENCIES) | BIT(HYPERV_FEAT_REENLIGHTENMENT) |
+ BIT(HYPERV_FEAT_TLBFLUSH) | BIT(HYPERV_FEAT_IPI) |
+ BIT(HYPERV_FEAT_STIMER_DIRECT);
+
+ /* Enlightened VMCS is only available on Intel/VMX */
+ if (kvm_hv_evmcs_available()) {
+ cpu->hyperv_default_features |= BIT(HYPERV_FEAT_EVMCS);
+ }
}
static int64_t x86_cpu_get_arch_id(CPUState *cs)
@@ -7486,6 +7534,10 @@ static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
x86_hv_passthrough_get,
x86_hv_passthrough_set);
+ object_class_property_add_bool(oc, "hv-default",
+ x86_hv_default_get,
+ x86_hv_default_set);
+
for (w = 0; w < FEATURE_WORDS; w++) {
int bitnr;
for (bitnr = 0; bitnr < 64; bitnr++) {
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index b4fbd46f0fc9..59350e70fb51 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1670,6 +1670,9 @@ struct X86CPU {
uint64_t hyperv_features_on;
uint64_t hyperv_features_off;
bool hyperv_passthrough;
+ /* 'hv-default' enablement */
+ uint64_t hyperv_default_features;
+ bool hyperv_default;
OnOffAuto hyperv_no_nonarch_cs;
uint32_t hyperv_vendor_id[3];
uint32_t hyperv_interface_id[4];
--
2.29.2
On Wed, 10 Feb 2021 17:40:32 +0100
Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
> Enabling Hyper-V emulation for a Windows VM is a tiring experience as it
> requires listing all currently supported enlightenments ("hv-*" CPU
> features) explicitly. We do have 'hv-passthrough' mode enabling
> everything but it can't be used in production as it prevents migration.
>
> Introduce a simple 'hv-default=on' CPU flag enabling all currently supported
> Hyper-V enlightenments. Later, when new enlightenments get implemented,
> compat_props mechanism will be used to disable them for legacy machine types,
> this will keep 'hv-default=on' configurations migratable.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
> docs/hyperv.txt | 16 ++++++++++++---
> target/i386/cpu.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
> target/i386/cpu.h | 3 +++
> 3 files changed, 68 insertions(+), 3 deletions(-)
>
> diff --git a/docs/hyperv.txt b/docs/hyperv.txt
> index 5df00da54fc4..a54c066cab09 100644
> --- a/docs/hyperv.txt
> +++ b/docs/hyperv.txt
> @@ -17,10 +17,20 @@ compatible hypervisor and use Hyper-V specific features.
>
> 2. Setup
> =========
> -No Hyper-V enlightenments are enabled by default by either KVM or QEMU. In
> -QEMU, individual enlightenments can be enabled through CPU flags, e.g:
> +All currently supported Hyper-V enlightenments can be enabled by specifying
> +'hv-default=on' CPU flag:
>
> - qemu-system-x86_64 --enable-kvm --cpu host,hv_relaxed,hv_vpindex,hv_time, ...
> + qemu-system-x86_64 --enable-kvm --cpu host,hv-default ...
> +
> +Alternatively, it is possible to do fine-grained enablement through CPU flags,
> +e.g:
> +
> + qemu-system-x86_64 --enable-kvm --cpu host,hv-relaxed,hv-vpindex,hv-time ...
> +
> +It is also possible to disable individual enlightenments from the default list,
> +this can be used for debugging purposes:
> +
> + qemu-system-x86_64 --enable-kvm --cpu host,hv-default=on,hv-evmcs=off ...
>
> Sometimes there are dependencies between enlightenments, QEMU is supposed to
> check that the supplied configuration is sane.
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index f8df2caed779..013aa60272d8 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -4736,6 +4736,12 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
> {
> X86CPU *cpu = X86_CPU(obj);
>
> + if (cpu->hyperv_default) {
> + error_setg(errp,
> + "'hv-default' and 'hv-paththrough' are mutually exclusive");
> + return;
> + }
> +
> cpu->hyperv_passthrough = value;
>
> /* hv-passthrough overrides everything with what's supported by the host */
> @@ -4748,6 +4754,33 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
> return;
> }
>
> +static bool x86_hv_default_get(Object *obj, Error **errp)
> +{
> + X86CPU *cpu = X86_CPU(obj);
> +
> + return cpu->hyperv_default;
> +}
> +
> +static void x86_hv_default_set(Object *obj, bool value, Error **errp)
> +{
> + X86CPU *cpu = X86_CPU(obj);
> +
> + if (cpu->hyperv_passthrough) {
> + error_setg(errp,
> + "'hv-default' and 'hv-paththrough' are mutually exclusive");
this check will work only half way, i.e.: hv-paththrough=on,hv-default=on|off
(where off value looks a bit wierd)
but not other way around: hv-default=on,hv-paththrough=on
were you thinking about following error:
"hv-default can't be used after hv-paththrough were enabled"
or if it symmetric, then putting this check in realizefn() will do the job
as both properties are processed by that time.
> + return;
> + }
> +
> + cpu->hyperv_default = value;
> +
> + /* hv-default overrides everything with the default set */
> + if (value) {
> + cpu->hyperv_features = cpu->hyperv_default_features;
> + cpu->hyperv_features_on = 0;
> + cpu->hyperv_features_off = 0;
> + }
> +}
> +
> /* Generic getter for "feature-words" and "filtered-features" properties */
> static void x86_cpu_get_feature_words(Object *obj, Visitor *v,
> const char *name, void *opaque,
> @@ -7152,6 +7185,21 @@ static void x86_cpu_initfn(Object *obj)
> if (xcc->model) {
> x86_cpu_load_model(cpu, xcc->model);
> }
> +
> + /* Hyper-V features enabled with 'hv-default=on' */
> + cpu->hyperv_default_features = BIT(HYPERV_FEAT_RELAXED) |
> + BIT(HYPERV_FEAT_VAPIC) | BIT(HYPERV_FEAT_TIME) |
> + BIT(HYPERV_FEAT_CRASH) | BIT(HYPERV_FEAT_RESET) |
> + BIT(HYPERV_FEAT_VPINDEX) | BIT(HYPERV_FEAT_RUNTIME) |
> + BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_STIMER) |
> + BIT(HYPERV_FEAT_FREQUENCIES) | BIT(HYPERV_FEAT_REENLIGHTENMENT) |
> + BIT(HYPERV_FEAT_TLBFLUSH) | BIT(HYPERV_FEAT_IPI) |
> + BIT(HYPERV_FEAT_STIMER_DIRECT);
> +
> + /* Enlightened VMCS is only available on Intel/VMX */
> + if (kvm_hv_evmcs_available()) {
> + cpu->hyperv_default_features |= BIT(HYPERV_FEAT_EVMCS);
> + }
> }
>
> static int64_t x86_cpu_get_arch_id(CPUState *cs)
> @@ -7486,6 +7534,10 @@ static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
> x86_hv_passthrough_get,
> x86_hv_passthrough_set);
>
> + object_class_property_add_bool(oc, "hv-default",
> + x86_hv_default_get,
> + x86_hv_default_set);
> +
> for (w = 0; w < FEATURE_WORDS; w++) {
> int bitnr;
> for (bitnr = 0; bitnr < 64; bitnr++) {
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index b4fbd46f0fc9..59350e70fb51 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1670,6 +1670,9 @@ struct X86CPU {
> uint64_t hyperv_features_on;
> uint64_t hyperv_features_off;
> bool hyperv_passthrough;
> + /* 'hv-default' enablement */
> + uint64_t hyperv_default_features;
> + bool hyperv_default;
> OnOffAuto hyperv_no_nonarch_cs;
> uint32_t hyperv_vendor_id[3];
> uint32_t hyperv_interface_id[4];
Igor Mammedov <imammedo@redhat.com> writes:
> On Wed, 10 Feb 2021 17:40:32 +0100
> Vitaly Kuznetsov <vkuznets@redhat.com> wrote:
>
>> Enabling Hyper-V emulation for a Windows VM is a tiring experience as it
>> requires listing all currently supported enlightenments ("hv-*" CPU
>> features) explicitly. We do have 'hv-passthrough' mode enabling
>> everything but it can't be used in production as it prevents migration.
>>
>> Introduce a simple 'hv-default=on' CPU flag enabling all currently supported
>> Hyper-V enlightenments. Later, when new enlightenments get implemented,
>> compat_props mechanism will be used to disable them for legacy machine types,
>> this will keep 'hv-default=on' configurations migratable.
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>> docs/hyperv.txt | 16 ++++++++++++---
>> target/i386/cpu.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++
>> target/i386/cpu.h | 3 +++
>> 3 files changed, 68 insertions(+), 3 deletions(-)
>>
>> diff --git a/docs/hyperv.txt b/docs/hyperv.txt
>> index 5df00da54fc4..a54c066cab09 100644
>> --- a/docs/hyperv.txt
>> +++ b/docs/hyperv.txt
>> @@ -17,10 +17,20 @@ compatible hypervisor and use Hyper-V specific features.
>>
>> 2. Setup
>> =========
>> -No Hyper-V enlightenments are enabled by default by either KVM or QEMU. In
>> -QEMU, individual enlightenments can be enabled through CPU flags, e.g:
>> +All currently supported Hyper-V enlightenments can be enabled by specifying
>> +'hv-default=on' CPU flag:
>>
>> - qemu-system-x86_64 --enable-kvm --cpu host,hv_relaxed,hv_vpindex,hv_time, ...
>> + qemu-system-x86_64 --enable-kvm --cpu host,hv-default ...
>> +
>> +Alternatively, it is possible to do fine-grained enablement through CPU flags,
>> +e.g:
>> +
>> + qemu-system-x86_64 --enable-kvm --cpu host,hv-relaxed,hv-vpindex,hv-time ...
>> +
>> +It is also possible to disable individual enlightenments from the default list,
>> +this can be used for debugging purposes:
>> +
>> + qemu-system-x86_64 --enable-kvm --cpu host,hv-default=on,hv-evmcs=off ...
>>
>> Sometimes there are dependencies between enlightenments, QEMU is supposed to
>> check that the supplied configuration is sane.
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index f8df2caed779..013aa60272d8 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -4736,6 +4736,12 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
>> {
>> X86CPU *cpu = X86_CPU(obj);
>>
>> + if (cpu->hyperv_default) {
^^^ here ^^^
>> + error_setg(errp,
>> + "'hv-default' and 'hv-paththrough' are mutually exclusive");
>> + return;
>> + }
>> +
>> cpu->hyperv_passthrough = value;
>>
>> /* hv-passthrough overrides everything with what's supported by the host */
>> @@ -4748,6 +4754,33 @@ static void x86_hv_passthrough_set(Object *obj, bool value, Error **errp)
>> return;
>> }
>>
>> +static bool x86_hv_default_get(Object *obj, Error **errp)
>> +{
>> + X86CPU *cpu = X86_CPU(obj);
>> +
>> + return cpu->hyperv_default;
>> +}
>> +
>> +static void x86_hv_default_set(Object *obj, bool value, Error **errp)
>> +{
>> + X86CPU *cpu = X86_CPU(obj);
>> +
>> + if (cpu->hyperv_passthrough) {
>> + error_setg(errp,
>> + "'hv-default' and 'hv-paththrough' are mutually exclusive");
> this check will work only half way, i.e.: hv-paththrough=on,hv-default=on|off
> (where off value looks a bit wierd)
> but not other way around: hv-default=on,hv-paththrough=on
The check in x86_hv_passthrough_set() chechs the opposite scenario.
>
> were you thinking about following error:
> "hv-default can't be used after hv-paththrough were enabled"
>
> or if it symmetric, then putting this check in realizefn() will do the job
> as both properties are processed by that time.
I can move the check there but I think that two checks I add here cover
what we need (and we don't need to care what to set 'hyperv_features' to
in the interim).
>
>> + return;
>> + }
>> +
>> + cpu->hyperv_default = value;
>> +
>> + /* hv-default overrides everything with the default set */
>> + if (value) {
>> + cpu->hyperv_features = cpu->hyperv_default_features;
>> + cpu->hyperv_features_on = 0;
>> + cpu->hyperv_features_off = 0;
>> + }
>> +}
>> +
>> /* Generic getter for "feature-words" and "filtered-features" properties */
>> static void x86_cpu_get_feature_words(Object *obj, Visitor *v,
>> const char *name, void *opaque,
>> @@ -7152,6 +7185,21 @@ static void x86_cpu_initfn(Object *obj)
>> if (xcc->model) {
>> x86_cpu_load_model(cpu, xcc->model);
>> }
>> +
>> + /* Hyper-V features enabled with 'hv-default=on' */
>> + cpu->hyperv_default_features = BIT(HYPERV_FEAT_RELAXED) |
>> + BIT(HYPERV_FEAT_VAPIC) | BIT(HYPERV_FEAT_TIME) |
>> + BIT(HYPERV_FEAT_CRASH) | BIT(HYPERV_FEAT_RESET) |
>> + BIT(HYPERV_FEAT_VPINDEX) | BIT(HYPERV_FEAT_RUNTIME) |
>> + BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_STIMER) |
>> + BIT(HYPERV_FEAT_FREQUENCIES) | BIT(HYPERV_FEAT_REENLIGHTENMENT) |
>> + BIT(HYPERV_FEAT_TLBFLUSH) | BIT(HYPERV_FEAT_IPI) |
>> + BIT(HYPERV_FEAT_STIMER_DIRECT);
>> +
>> + /* Enlightened VMCS is only available on Intel/VMX */
>> + if (kvm_hv_evmcs_available()) {
>> + cpu->hyperv_default_features |= BIT(HYPERV_FEAT_EVMCS);
>> + }
>> }
>>
>> static int64_t x86_cpu_get_arch_id(CPUState *cs)
>> @@ -7486,6 +7534,10 @@ static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
>> x86_hv_passthrough_get,
>> x86_hv_passthrough_set);
>>
>> + object_class_property_add_bool(oc, "hv-default",
>> + x86_hv_default_get,
>> + x86_hv_default_set);
>> +
>> for (w = 0; w < FEATURE_WORDS; w++) {
>> int bitnr;
>> for (bitnr = 0; bitnr < 64; bitnr++) {
>> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>> index b4fbd46f0fc9..59350e70fb51 100644
>> --- a/target/i386/cpu.h
>> +++ b/target/i386/cpu.h
>> @@ -1670,6 +1670,9 @@ struct X86CPU {
>> uint64_t hyperv_features_on;
>> uint64_t hyperv_features_off;
>> bool hyperv_passthrough;
>> + /* 'hv-default' enablement */
>> + uint64_t hyperv_default_features;
>> + bool hyperv_default;
>> OnOffAuto hyperv_no_nonarch_cs;
>> uint32_t hyperv_vendor_id[3];
>> uint32_t hyperv_interface_id[4];
>
--
Vitaly
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