[PATCH v6 4/5] hyperv: Do not overlap the hvcall IO areas in get_vtl()

Roman Kisel
2025-01-08T22:21:41Z

The Top-Level Functional Specification for Hyper-V, Section 3.6 [1, 2],
disallows overlapping of the input and output hypercall areas, and
get_vtl(void) does overlap them.

Use the output hypercall page of the current vCPU for the hypercall.

[1] https://learn.microsoft.com/en-us/virtualization/hyper-v-on-windows/tlfs/hypercall-interface
[2] https://github.com/MicrosoftDocs/Virtualization-Documentation/tree/main/tlfs

Fixes: 8387ce06d70b ("x86/hyperv: Set Virtual Trust Level in VMBus init message")
Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Tianyu Lan <tiala@microsoft.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
---
arch/x86/hyperv/hv_init.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index f82d1aefaa8a..173005e6a95d 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -422,7 +422,7 @@ static u8 __init get_vtl(void)

local_irq_save(flags);
input = *this_cpu_ptr(hyperv_pcpu_input_arg);
- output = (struct hv_output_get_vp_registers *)input;
+ output = *this_cpu_ptr(hyperv_pcpu_output_arg);

memset(input, 0, struct_size(input, names, 1));
input->partition_id = HV_PARTITION_ID_SELF;
--
2.34.1