Replace TARGET_PAGE.* by runtime calls
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
---
hw/hyperv/syndbg.c | 7 ++++---
hw/hyperv/meson.build | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
index d3e39170772..f9382202ed3 100644
--- a/hw/hyperv/syndbg.c
+++ b/hw/hyperv/syndbg.c
@@ -14,7 +14,7 @@
#include "migration/vmstate.h"
#include "hw/qdev-properties.h"
#include "hw/loader.h"
-#include "cpu.h"
+#include "exec/target_page.h"
#include "hw/hyperv/hyperv.h"
#include "hw/hyperv/vmbus-bridge.h"
#include "hw/hyperv/hyperv-proto.h"
@@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg, uint64_t outgpa,
uint64_t timeout, uint32_t *retrieved_count)
{
uint16_t ret;
- uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
+ const size_t buf_size = qemu_target_page_size() - UDP_PKT_HEADER_SIZE;
+ uint8_t *data_buf = g_alloca(buf_size);
hwaddr out_len;
void *out_data;
ssize_t recv_byte_count;
@@ -201,7 +202,7 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg, uint64_t outgpa,
recv_byte_count = 0;
} else {
recv_byte_count = recv(syndbg->socket, data_buf,
- MIN(sizeof(data_buf), count), MSG_WAITALL);
+ MIN(buf_size, count), MSG_WAITALL);
if (recv_byte_count == -1) {
return HV_STATUS_INVALID_PARAMETER;
}
diff --git a/hw/hyperv/meson.build b/hw/hyperv/meson.build
index c855fdcf04c..a9f2045a9af 100644
--- a/hw/hyperv/meson.build
+++ b/hw/hyperv/meson.build
@@ -1,6 +1,6 @@
specific_ss.add(when: 'CONFIG_HYPERV', if_true: files('hyperv.c'))
specific_ss.add(when: 'CONFIG_HYPERV_TESTDEV', if_true: files('hyperv_testdev.c'))
system_ss.add(when: 'CONFIG_VMBUS', if_true: files('vmbus.c'))
-specific_ss.add(when: 'CONFIG_SYNDBG', if_true: files('syndbg.c'))
+system_ss.add(when: 'CONFIG_SYNDBG', if_true: files('syndbg.c'))
specific_ss.add(when: 'CONFIG_HV_BALLOON', if_true: files('hv-balloon.c', 'hv-balloon-page_range_tree.c', 'hv-balloon-our_range_memslots.c'))
system_ss.add(when: 'CONFIG_HV_BALLOON', if_false: files('hv-balloon-stub.c'))
--
2.39.5On 3/5/25 22:41, Pierrick Bouvier wrote:
> Replace TARGET_PAGE.* by runtime calls
>
> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> ---
> hw/hyperv/syndbg.c | 7 ++++---
> hw/hyperv/meson.build | 2 +-
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
> index d3e39170772..f9382202ed3 100644
> --- a/hw/hyperv/syndbg.c
> +++ b/hw/hyperv/syndbg.c
> @@ -14,7 +14,7 @@
> #include "migration/vmstate.h"
> #include "hw/qdev-properties.h"
> #include "hw/loader.h"
> -#include "cpu.h"
> +#include "exec/target_page.h"
> #include "hw/hyperv/hyperv.h"
> #include "hw/hyperv/vmbus-bridge.h"
> #include "hw/hyperv/hyperv-proto.h"
> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg, uint64_t outgpa,
> uint64_t timeout, uint32_t *retrieved_count)
> {
> uint16_t ret;
> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
> + const size_t buf_size = qemu_target_page_size() - UDP_PKT_HEADER_SIZE;
> + uint8_t *data_buf = g_alloca(buf_size);
> hwaddr out_len;
> void *out_data;
> ssize_t recv_byte_count;
We've purged the code base of VLAs, and those are preferable to alloca.
Just use g_malloc and g_autofree.
r~
On 3/6/25 08:19, Richard Henderson wrote:
> On 3/5/25 22:41, Pierrick Bouvier wrote:
>> Replace TARGET_PAGE.* by runtime calls
>>
>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>> ---
>> hw/hyperv/syndbg.c | 7 ++++---
>> hw/hyperv/meson.build | 2 +-
>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>> index d3e39170772..f9382202ed3 100644
>> --- a/hw/hyperv/syndbg.c
>> +++ b/hw/hyperv/syndbg.c
>> @@ -14,7 +14,7 @@
>> #include "migration/vmstate.h"
>> #include "hw/qdev-properties.h"
>> #include "hw/loader.h"
>> -#include "cpu.h"
>> +#include "exec/target_page.h"
>> #include "hw/hyperv/hyperv.h"
>> #include "hw/hyperv/vmbus-bridge.h"
>> #include "hw/hyperv/hyperv-proto.h"
>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg, uint64_t outgpa,
>> uint64_t timeout, uint32_t *retrieved_count)
>> {
>> uint16_t ret;
>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>> + const size_t buf_size = qemu_target_page_size() - UDP_PKT_HEADER_SIZE;
>> + uint8_t *data_buf = g_alloca(buf_size);
>> hwaddr out_len;
>> void *out_data;
>> ssize_t recv_byte_count;
>
> We've purged the code base of VLAs, and those are preferable to alloca.
> Just use g_malloc and g_autofree.
>
I hesitated, due to potential performance considerations for people
reviewing the patch. I'll switch to heap based storage.
>
> r~
On 6/3/25 17:23, Pierrick Bouvier wrote:
> On 3/6/25 08:19, Richard Henderson wrote:
>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>> Replace TARGET_PAGE.* by runtime calls
>>>
>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>> ---
>>> hw/hyperv/syndbg.c | 7 ++++---
>>> hw/hyperv/meson.build | 2 +-
>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>> index d3e39170772..f9382202ed3 100644
>>> --- a/hw/hyperv/syndbg.c
>>> +++ b/hw/hyperv/syndbg.c
>>> @@ -14,7 +14,7 @@
>>> #include "migration/vmstate.h"
>>> #include "hw/qdev-properties.h"
>>> #include "hw/loader.h"
>>> -#include "cpu.h"
>>> +#include "exec/target_page.h"
>>> #include "hw/hyperv/hyperv.h"
>>> #include "hw/hyperv/vmbus-bridge.h"
>>> #include "hw/hyperv/hyperv-proto.h"
>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>> uint64_t outgpa,
>>> uint64_t timeout, uint32_t
>>> *retrieved_count)
>>> {
>>> uint16_t ret;
>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>> + const size_t buf_size = qemu_target_page_size() -
>>> UDP_PKT_HEADER_SIZE;
>>> + uint8_t *data_buf = g_alloca(buf_size);
>>> hwaddr out_len;
>>> void *out_data;
>>> ssize_t recv_byte_count;
>>
>> We've purged the code base of VLAs, and those are preferable to alloca.
>> Just use g_malloc and g_autofree.
>>
>
> I hesitated, due to potential performance considerations for people
> reviewing the patch. I'll switch to heap based storage.
OTOH hyperv is x86-only, so we could do:
#define BUFSZ (4 * KiB)
handle_recv_msg()
{
uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
...
hv_syndbg_class_init()
{
assert(BUFSZ > qemu_target_page_size());
...
and call it a day.
On 3/6/25 09:58, Philippe Mathieu-Daudé wrote:
> On 6/3/25 17:23, Pierrick Bouvier wrote:
>> On 3/6/25 08:19, Richard Henderson wrote:
>>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>>> Replace TARGET_PAGE.* by runtime calls
>>>>
>>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>>> ---
>>>> hw/hyperv/syndbg.c | 7 ++++---
>>>> hw/hyperv/meson.build | 2 +-
>>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>>> index d3e39170772..f9382202ed3 100644
>>>> --- a/hw/hyperv/syndbg.c
>>>> +++ b/hw/hyperv/syndbg.c
>>>> @@ -14,7 +14,7 @@
>>>> #include "migration/vmstate.h"
>>>> #include "hw/qdev-properties.h"
>>>> #include "hw/loader.h"
>>>> -#include "cpu.h"
>>>> +#include "exec/target_page.h"
>>>> #include "hw/hyperv/hyperv.h"
>>>> #include "hw/hyperv/vmbus-bridge.h"
>>>> #include "hw/hyperv/hyperv-proto.h"
>>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>>> uint64_t outgpa,
>>>> uint64_t timeout, uint32_t
>>>> *retrieved_count)
>>>> {
>>>> uint16_t ret;
>>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>>> + const size_t buf_size = qemu_target_page_size() -
>>>> UDP_PKT_HEADER_SIZE;
>>>> + uint8_t *data_buf = g_alloca(buf_size);
>>>> hwaddr out_len;
>>>> void *out_data;
>>>> ssize_t recv_byte_count;
>>>
>>> We've purged the code base of VLAs, and those are preferable to alloca.
>>> Just use g_malloc and g_autofree.
>>>
>>
>> I hesitated, due to potential performance considerations for people
>> reviewing the patch. I'll switch to heap based storage.
>
> OTOH hyperv is x86-only, so we could do:
>
> #define BUFSZ (4 * KiB)
>
> handle_recv_msg()
> {
> uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
> ...
>
> hv_syndbg_class_init()
> {
> assert(BUFSZ > qemu_target_page_size());
> ...
>
> and call it a day.
Could be possible for now yes.
Any opinion from concerned maintainers?
On 6.03.2025 23:56, Pierrick Bouvier wrote:
> On 3/6/25 09:58, Philippe Mathieu-Daudé wrote:
>> On 6/3/25 17:23, Pierrick Bouvier wrote:
>>> On 3/6/25 08:19, Richard Henderson wrote:
>>>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>>>> Replace TARGET_PAGE.* by runtime calls
>>>>>
>>>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>>>> ---
>>>>> hw/hyperv/syndbg.c | 7 ++++---
>>>>> hw/hyperv/meson.build | 2 +-
>>>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>>>
>>>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>>>> index d3e39170772..f9382202ed3 100644
>>>>> --- a/hw/hyperv/syndbg.c
>>>>> +++ b/hw/hyperv/syndbg.c
>>>>> @@ -14,7 +14,7 @@
>>>>> #include "migration/vmstate.h"
>>>>> #include "hw/qdev-properties.h"
>>>>> #include "hw/loader.h"
>>>>> -#include "cpu.h"
>>>>> +#include "exec/target_page.h"
>>>>> #include "hw/hyperv/hyperv.h"
>>>>> #include "hw/hyperv/vmbus-bridge.h"
>>>>> #include "hw/hyperv/hyperv-proto.h"
>>>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>>>> uint64_t outgpa,
>>>>> uint64_t timeout, uint32_t
>>>>> *retrieved_count)
>>>>> {
>>>>> uint16_t ret;
>>>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>>>> + const size_t buf_size = qemu_target_page_size() -
>>>>> UDP_PKT_HEADER_SIZE;
>>>>> + uint8_t *data_buf = g_alloca(buf_size);
>>>>> hwaddr out_len;
>>>>> void *out_data;
>>>>> ssize_t recv_byte_count;
>>>>
>>>> We've purged the code base of VLAs, and those are preferable to alloca.
>>>> Just use g_malloc and g_autofree.
>>>>
>>>
>>> I hesitated, due to potential performance considerations for people
>>> reviewing the patch. I'll switch to heap based storage.
>>
>> OTOH hyperv is x86-only, so we could do:
>>
>> #define BUFSZ (4 * KiB)
>>
>> handle_recv_msg()
>> {
>> uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
>> ...
>>
>> hv_syndbg_class_init()
>> {
>> assert(BUFSZ > qemu_target_page_size());
>> ...
>>
>> and call it a day.
>
> Could be possible for now yes.
>
> Any opinion from concerned maintainers?
I think essentially hardcoding 4k pages in hyperv is okay
(with an appropriate checking/enforcement asserts() of course),
since even if this gets ported to ARM64 at some point
it is going to need *a lot* of changes anyway.
Thanks,
Maciej
On 3/7/25 03:07, Maciej S. Szmigiero wrote:
> On 6.03.2025 23:56, Pierrick Bouvier wrote:
>> On 3/6/25 09:58, Philippe Mathieu-Daudé wrote:
>>> On 6/3/25 17:23, Pierrick Bouvier wrote:
>>>> On 3/6/25 08:19, Richard Henderson wrote:
>>>>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>>>>> Replace TARGET_PAGE.* by runtime calls
>>>>>>
>>>>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>>>>> ---
>>>>>> hw/hyperv/syndbg.c | 7 ++++---
>>>>>> hw/hyperv/meson.build | 2 +-
>>>>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>>>>> index d3e39170772..f9382202ed3 100644
>>>>>> --- a/hw/hyperv/syndbg.c
>>>>>> +++ b/hw/hyperv/syndbg.c
>>>>>> @@ -14,7 +14,7 @@
>>>>>> #include "migration/vmstate.h"
>>>>>> #include "hw/qdev-properties.h"
>>>>>> #include "hw/loader.h"
>>>>>> -#include "cpu.h"
>>>>>> +#include "exec/target_page.h"
>>>>>> #include "hw/hyperv/hyperv.h"
>>>>>> #include "hw/hyperv/vmbus-bridge.h"
>>>>>> #include "hw/hyperv/hyperv-proto.h"
>>>>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>>>>> uint64_t outgpa,
>>>>>> uint64_t timeout, uint32_t
>>>>>> *retrieved_count)
>>>>>> {
>>>>>> uint16_t ret;
>>>>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>>>>> + const size_t buf_size = qemu_target_page_size() -
>>>>>> UDP_PKT_HEADER_SIZE;
>>>>>> + uint8_t *data_buf = g_alloca(buf_size);
>>>>>> hwaddr out_len;
>>>>>> void *out_data;
>>>>>> ssize_t recv_byte_count;
>>>>>
>>>>> We've purged the code base of VLAs, and those are preferable to alloca.
>>>>> Just use g_malloc and g_autofree.
>>>>>
>>>>
>>>> I hesitated, due to potential performance considerations for people
>>>> reviewing the patch. I'll switch to heap based storage.
>>>
>>> OTOH hyperv is x86-only, so we could do:
>>>
>>> #define BUFSZ (4 * KiB)
>>>
>>> handle_recv_msg()
>>> {
>>> uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
>>> ...
>>>
>>> hv_syndbg_class_init()
>>> {
>>> assert(BUFSZ > qemu_target_page_size());
>>> ...
>>>
>>> and call it a day.
>>
>> Could be possible for now yes.
>>
>> Any opinion from concerned maintainers?
>
> I think essentially hardcoding 4k pages in hyperv is okay
> (with an appropriate checking/enforcement asserts() of course),
> since even if this gets ported to ARM64 at some point
> it is going to need *a lot* of changes anyway.
>
Ok, I will hardcode this following Philippe suggestion then.
> Thanks,
> Maciej
>
"Maciej S. Szmigiero" <mail@maciej.szmigiero.name> writes:
> On 6.03.2025 23:56, Pierrick Bouvier wrote:
>> On 3/6/25 09:58, Philippe Mathieu-Daudé wrote:
>>> On 6/3/25 17:23, Pierrick Bouvier wrote:
>>>> On 3/6/25 08:19, Richard Henderson wrote:
>>>>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>>>>> Replace TARGET_PAGE.* by runtime calls
>>>>>>
>>>>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>>>>> ---
>>>>>> hw/hyperv/syndbg.c | 7 ++++---
>>>>>> hw/hyperv/meson.build | 2 +-
>>>>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>>>>
>>>>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>>>>> index d3e39170772..f9382202ed3 100644
>>>>>> --- a/hw/hyperv/syndbg.c
>>>>>> +++ b/hw/hyperv/syndbg.c
>>>>>> @@ -14,7 +14,7 @@
>>>>>> #include "migration/vmstate.h"
>>>>>> #include "hw/qdev-properties.h"
>>>>>> #include "hw/loader.h"
>>>>>> -#include "cpu.h"
>>>>>> +#include "exec/target_page.h"
>>>>>> #include "hw/hyperv/hyperv.h"
>>>>>> #include "hw/hyperv/vmbus-bridge.h"
>>>>>> #include "hw/hyperv/hyperv-proto.h"
>>>>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>>>>> uint64_t outgpa,
>>>>>> uint64_t timeout, uint32_t
>>>>>> *retrieved_count)
>>>>>> {
>>>>>> uint16_t ret;
>>>>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>>>>> + const size_t buf_size = qemu_target_page_size() -
>>>>>> UDP_PKT_HEADER_SIZE;
>>>>>> + uint8_t *data_buf = g_alloca(buf_size);
>>>>>> hwaddr out_len;
>>>>>> void *out_data;
>>>>>> ssize_t recv_byte_count;
>>>>>
>>>>> We've purged the code base of VLAs, and those are preferable to alloca.
>>>>> Just use g_malloc and g_autofree.
>>>>>
>>>>
>>>> I hesitated, due to potential performance considerations for people
>>>> reviewing the patch. I'll switch to heap based storage.
>>>
>>> OTOH hyperv is x86-only, so we could do:
>>>
>>> #define BUFSZ (4 * KiB)
>>>
>>> handle_recv_msg()
>>> {
>>> uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
>>> ...
>>>
>>> hv_syndbg_class_init()
>>> {
>>> assert(BUFSZ > qemu_target_page_size());
>>> ...
>>>
>>> and call it a day.
>> Could be possible for now yes.
>> Any opinion from concerned maintainers?
>
> I think essentially hardcoding 4k pages in hyperv is okay
> (with an appropriate checking/enforcement asserts() of course),
> since even if this gets ported to ARM64 at some point
> it is going to need *a lot* of changes anyway.
There was a talk at last years KVM Forum about porting WHPX for Windows
on Arm:
https://kvm-forum.qemu.org/2024/Qemu_support_for_Windows_on_Arm_GgKlLjf.pdf
but am I right in thinking all the hyperv code in QEMU is about
providing guest facing enlightenments for Windows guests under KVM? I
guess no one is working on that at the moment.
>
> Thanks,
> Maciej
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
On 7.03.2025 15:50, Alex Bennée wrote:
> "Maciej S. Szmigiero" <mail@maciej.szmigiero.name> writes:
>
>> On 6.03.2025 23:56, Pierrick Bouvier wrote:
>>> On 3/6/25 09:58, Philippe Mathieu-Daudé wrote:
>>>> On 6/3/25 17:23, Pierrick Bouvier wrote:
>>>>> On 3/6/25 08:19, Richard Henderson wrote:
>>>>>> On 3/5/25 22:41, Pierrick Bouvier wrote:
>>>>>>> Replace TARGET_PAGE.* by runtime calls
>>>>>>>
>>>>>>> Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
>>>>>>> ---
>>>>>>> hw/hyperv/syndbg.c | 7 ++++---
>>>>>>> hw/hyperv/meson.build | 2 +-
>>>>>>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>>>>>>
>>>>>>> diff --git a/hw/hyperv/syndbg.c b/hw/hyperv/syndbg.c
>>>>>>> index d3e39170772..f9382202ed3 100644
>>>>>>> --- a/hw/hyperv/syndbg.c
>>>>>>> +++ b/hw/hyperv/syndbg.c
>>>>>>> @@ -14,7 +14,7 @@
>>>>>>> #include "migration/vmstate.h"
>>>>>>> #include "hw/qdev-properties.h"
>>>>>>> #include "hw/loader.h"
>>>>>>> -#include "cpu.h"
>>>>>>> +#include "exec/target_page.h"
>>>>>>> #include "hw/hyperv/hyperv.h"
>>>>>>> #include "hw/hyperv/vmbus-bridge.h"
>>>>>>> #include "hw/hyperv/hyperv-proto.h"
>>>>>>> @@ -188,7 +188,8 @@ static uint16_t handle_recv_msg(HvSynDbg *syndbg,
>>>>>>> uint64_t outgpa,
>>>>>>> uint64_t timeout, uint32_t
>>>>>>> *retrieved_count)
>>>>>>> {
>>>>>>> uint16_t ret;
>>>>>>> - uint8_t data_buf[TARGET_PAGE_SIZE - UDP_PKT_HEADER_SIZE];
>>>>>>> + const size_t buf_size = qemu_target_page_size() -
>>>>>>> UDP_PKT_HEADER_SIZE;
>>>>>>> + uint8_t *data_buf = g_alloca(buf_size);
>>>>>>> hwaddr out_len;
>>>>>>> void *out_data;
>>>>>>> ssize_t recv_byte_count;
>>>>>>
>>>>>> We've purged the code base of VLAs, and those are preferable to alloca.
>>>>>> Just use g_malloc and g_autofree.
>>>>>>
>>>>>
>>>>> I hesitated, due to potential performance considerations for people
>>>>> reviewing the patch. I'll switch to heap based storage.
>>>>
>>>> OTOH hyperv is x86-only, so we could do:
>>>>
>>>> #define BUFSZ (4 * KiB)
>>>>
>>>> handle_recv_msg()
>>>> {
>>>> uint8_t data_buf[BUFSZ - UDP_PKT_HEADER_SIZE];
>>>> ...
>>>>
>>>> hv_syndbg_class_init()
>>>> {
>>>> assert(BUFSZ > qemu_target_page_size());
>>>> ...
>>>>
>>>> and call it a day.
>>> Could be possible for now yes.
>>> Any opinion from concerned maintainers?
>>
>> I think essentially hardcoding 4k pages in hyperv is okay
>> (with an appropriate checking/enforcement asserts() of course),
>> since even if this gets ported to ARM64 at some point
>> it is going to need *a lot* of changes anyway.
>
> There was a talk at last years KVM Forum about porting WHPX for Windows
> on Arm:
>
> https://kvm-forum.qemu.org/2024/Qemu_support_for_Windows_on_Arm_GgKlLjf.pdf
>
> but am I right in thinking all the hyperv code in QEMU is about
> providing guest facing enlightenments for Windows guests under KVM? I
> guess no one is working on that at the moment.
Yes, I think that talk was about running QEMU on actual Hyper-V hypervisor,
while the code in hw/hyperv is about QEMU emulating Hyper-V interfaces to
QEMU's VMs.
CONFIG_HYPERV in hw/hyperv/Kconfig is even marked as "depends on KVM".
Thanks,
Maciej
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