| Message ID | 20240514224508.212318-3-romank@linux.microsoft.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | arm64/hyperv: Support Virtual Trust Level Boot | expand |
From: Roman Kisel <romank@linux.microsoft.com> Sent: Tuesday, May 14, 2024 3:44 PM > > 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 <romank@linux.microsoft.com> > --- > 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
On 5/15/2024 6:37 AM, Michael Kelley wrote: > From: Roman Kisel <romank@linux.microsoft.com> Sent: Tuesday, May 14, 2024 3:44 PM >> >> 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 <romank@linux.microsoft.com> >> --- >> 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. I'll explore that, appreciate sharing the context! > > Michael
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 @@ -31,7 +31,7 @@ config HYPERV_VTL_MODE Select this option to build a Linux kernel to run at a VTL other than the normal VTL0, which currently is only VTL2. This option - initializes the x86 platform for VTL2, and adds the ability to boot + initializes the kernel to run in VTL2, and adds the ability to boot secondary CPUs directly into 64-bit context as required for VTLs other than 0. A kernel built with this option must run at VTL2, and will not run as a normal guest.
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 <romank@linux.microsoft.com> --- drivers/hv/Kconfig | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)