hyperv: Do not overlap the hvcall IO areas in hv_vtl_apicid_to_vp_id()

The Top-Level Functional Specification for Hyper-V, Section 3.6 [1, 2],
disallows overlapping of the input and output hypercall areas, and
hv_vtl_apicid_to_vp_id() overlaps 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

Reported-by: Michael Kelley <[email protected]>
Closes: https://lore.kernel.org/lkml/SN6PR02MB4157B98CD34781CC87A9D921D40D2@SN6PR02MB4157.namprd02.prod.outlook.com/
Signed-off-by: Roman Kisel <[email protected]>
Reviewed-by: Easwar Hariharan <[email protected]>
Reviewed-by: Nuno Das Neves <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <20250108222138.1623703[email protected]>

diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c
index 04775346369c59882d82fafb1b64c7804b3517cd..4e1b1e3b565841eb26f3a11e61fbae81edf4a174 100644 (file)
--- a/arch/x86/hyperv/hv_vtl.c
+++ b/arch/x86/hyperv/hv_vtl.c
@@ -189,7 +189,7 @@ static int hv_vtl_apicid_to_vp_id(u32 apic_id)
        input->partition_id = HV_PARTITION_ID_SELF;
        input->apic_ids[0] = apic_id;
 
-       output = (u32 *)input;
+       output = *this_cpu_ptr(hyperv_pcpu_output_arg);
 
        control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_ID_FROM_APIC_ID;
        status = hv_do_hypercall(control, input, output);