[PATCH v6 3/5] hyperv: Enable the hypercall output page for the VTL mode

Roman Kisel
2025-01-08T22:21:40Z

Due to the hypercall page not being allocated in the VTL mode,
the code resorts to using a part of the input page.

Allocate the hypercall output page in the VTL mode thus enabling
it to use it for output and share code with dom0.

Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
---
drivers/hv/hv_common.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index c6ed3ba4bf61..af5d1dc451f6 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -278,6 +278,11 @@ static void hv_kmsg_dump_register(void)
}
}

+static inline bool hv_output_page_exists(void)
+{
+ return hv_root_partition || IS_ENABLED(CONFIG_HYPERV_VTL_MODE);
+}
+
int __init hv_common_init(void)
{
int i;
@@ -340,7 +345,7 @@ int __init hv_common_init(void)
BUG_ON(!hyperv_pcpu_input_arg);

/* Allocate the per-CPU state for output arg for root */
- if (hv_root_partition) {
+ if (hv_output_page_exists()) {
hyperv_pcpu_output_arg = alloc_percpu(void *);
BUG_ON(!hyperv_pcpu_output_arg);
}
@@ -435,7 +440,7 @@ int hv_common_cpu_init(unsigned int cpu)
void **inputarg, **outputarg;
u64 msr_vp_index;
gfp_t flags;
- int pgcount = hv_root_partition ? 2 : 1;
+ const int pgcount = hv_output_page_exists() ? 2 : 1;
void *mem;
int ret;

@@ -453,7 +458,7 @@ int hv_common_cpu_init(unsigned int cpu)
if (!mem)
return -ENOMEM;

- if (hv_root_partition) {
+ if (hv_output_page_exists()) {
outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
*outputarg = (char *)mem + HV_HYP_PAGE_SIZE;
}
--
2.34.1