RE: [PATCH v2 2/6] drivers/hv: Enable VTL mode for arm64
From: Michael Kelley <hidden>
Date: 2024-05-15 13:37:13
Also in:
linux-acpi, linux-arch, linux-hyperv, linux-pci, lkml
From: Roman Kisel <redacted> Sent: Tuesday, May 14, 2024 3:44 PM
quoted hunk ↗ jump to hunk
Kconfig dependencies for arm64 guests on Hyper-V require that be ACPI enabled, and limit VTL mode to x86/x64. To enable VTL mode on arm64 as well, update the dependencies. Since VTL mode requires DeviceTree instead of ACPI, don't require arm64 guests on Hyper-V to have ACPI. Signed-off-by: Roman Kisel <redacted> --- drivers/hv/Kconfig | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig index 862c47b191af..a5cd1365e248 100644 --- a/drivers/hv/Kconfig +++ b/drivers/hv/Kconfig@@ -5,7 +5,7 @@ menu "Microsoft Hyper-V guest support" config HYPERV tristate "Microsoft Hyper-V client drivers" depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \ - || (ACPI && ARM64 && !CPU_BIG_ENDIAN) + || (ARM64 && !CPU_BIG_ENDIAN) select PARAVIRT select X86_HV_CALLBACK_VECTOR if X86 select OF_EARLY_FLATTREE if OF@@ -15,7 +15,7 @@ config HYPERV config HYPERV_VTL_MODE bool "Enable Linux to boot in VTL context" - depends on X86_64 && HYPERV + depends on HYPERV depends on SMP default n help
These changes make it possible to build a normal VTL 0 Hyper-V guest (i.e., CONFIG_HYPERV_VTL_MODE=n) if CONFIG_ACPI is not set, which won't work. While we can say "don't do that", it would be better if the Kconfig dependencies expressed that requirement. A possible fix is to remove the "depends on HYPERV" from HYPERV_VTL_MODE. Then for HYPERV, make the "depends on ACPI" be conditional on !HYPERV_VTL_MODE (for both ARM64 and X86). I think we originally had "depends on HYPERV" in HYPERV_VTL_MODE because there was a VTL-related function in a non-Hyper-V code path, and we wanted to prevent that code from running in non-Hyper-V environments. But in practice, that turned out not to work well because occasionally people would do an "all config" build where both CONFIG_HYPERV and CONFIG_HYPERV_VTL_MODE were set, and it would panic during boot in their non-Hyper-V environment. Such people were not happy. :-( So Saurabh made a relatively simple change (see commit 14058f72cf13e) that got the VTL code out of that non-Hyper-V code path. With that change, it shouldn't matter if someone sets CONFIG_HYPERV_VTL_MODE=y in a build where CONFIG_HYPERV=n. At least that's my theory. :-) Someone would need to check it carefully. Michael _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel