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

[Roman Kisel]

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 <rom...@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