| Message ID | 20250307220304.247725-3-romank@linux.microsoft.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Delegated to: | Krzysztof Wilczyński |
| Headers | show |
| Series | arm64: hyperv: Support Virtual Trust Level Boot | expand |
From: Roman Kisel <romank@linux.microsoft.com> Sent: Friday, March 7, 2025 2:03 PM > > The arm64 Hyper-V startup path relies on ACPI to detect > running under a Hyper-V compatible hypervisor. That > doesn't work on non-ACPI systems. > > Hoist the ACPI detection logic into a separate function. Then > use the vendor-specific hypervisor service call (implemented > recently in Hyper-V) via SMCCC in the non-ACPI case. > > Signed-off-by: Roman Kisel <romank@linux.microsoft.com> > --- > arch/arm64/hyperv/mshyperv.c | 43 +++++++++++++++++++++++++++++++----- > 1 file changed, 38 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c > index 29fcfd595f48..c647db56fd6b 100644 > --- a/arch/arm64/hyperv/mshyperv.c > +++ b/arch/arm64/hyperv/mshyperv.c > @@ -27,6 +27,41 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info > *info) > return 0; > } > > +static bool __init hyperv_detect_via_acpi(void) > +{ > + if (acpi_disabled) > + return false; > +#if IS_ENABLED(CONFIG_ACPI) > + /* > + * Hypervisor ID is only available in ACPI v6+, and the > + * structure layout was extended in v6 to accommodate that > + * new field. > + * > + * At the very minimum, this check makes sure not to read > + * past the FADT structure. > + * > + * It is also needed to catch running in some unknown > + * non-Hyper-V environment that has ACPI 5.x or less. > + * In such a case, it can't be Hyper-V. > + */ > + if (acpi_gbl_FADT.header.revision < 6) > + return false; > + return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0; > +#else > + return false; > +#endif > +} > + > +static bool __init hyperv_detect_via_smccc(void) > +{ > + uuid_t hyperv_uuid = UUID_INIT( > + 0x4d32ba58, 0x4764, 0xcd24, > + 0x75, 0x6c, 0xef, 0x8e, > + 0x24, 0x70, 0x59, 0x16); > + > + return arm_smccc_hyp_present(&hyperv_uuid); > +} > + > static int __init hyperv_init(void) > { > struct hv_get_vp_registers_output result; > @@ -35,13 +70,11 @@ static int __init hyperv_init(void) > > /* > * Allow for a kernel built with CONFIG_HYPERV to be running in > - * a non-Hyper-V environment, including on DT instead of ACPI. > + * a non-Hyper-V environment. > + * > * In such cases, do nothing and return success. > */ > - if (acpi_disabled) > - return 0; > - > - if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8)) > + if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc()) > return 0; > > /* Setup the guest ID */ > -- > 2.43.0 > Reviewed-by: Michael Kelley <mhklinux@outlook.com>
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c index 29fcfd595f48..c647db56fd6b 100644 --- a/arch/arm64/hyperv/mshyperv.c +++ b/arch/arm64/hyperv/mshyperv.c @@ -27,6 +27,41 @@ int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) return 0; } +static bool __init hyperv_detect_via_acpi(void) +{ + if (acpi_disabled) + return false; +#if IS_ENABLED(CONFIG_ACPI) + /* + * Hypervisor ID is only available in ACPI v6+, and the + * structure layout was extended in v6 to accommodate that + * new field. + * + * At the very minimum, this check makes sure not to read + * past the FADT structure. + * + * It is also needed to catch running in some unknown + * non-Hyper-V environment that has ACPI 5.x or less. + * In such a case, it can't be Hyper-V. + */ + if (acpi_gbl_FADT.header.revision < 6) + return false; + return strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8) == 0; +#else + return false; +#endif +} + +static bool __init hyperv_detect_via_smccc(void) +{ + uuid_t hyperv_uuid = UUID_INIT( + 0x4d32ba58, 0x4764, 0xcd24, + 0x75, 0x6c, 0xef, 0x8e, + 0x24, 0x70, 0x59, 0x16); + + return arm_smccc_hyp_present(&hyperv_uuid); +} + static int __init hyperv_init(void) { struct hv_get_vp_registers_output result; @@ -35,13 +70,11 @@ static int __init hyperv_init(void) /* * Allow for a kernel built with CONFIG_HYPERV to be running in - * a non-Hyper-V environment, including on DT instead of ACPI. + * a non-Hyper-V environment. + * * In such cases, do nothing and return success. */ - if (acpi_disabled) - return 0; - - if (strncmp((char *)&acpi_gbl_FADT.hypervisor_id, "MsHyperV", 8)) + if (!hyperv_detect_via_acpi() && !hyperv_detect_via_smccc()) return 0; /* Setup the guest ID */
The arm64 Hyper-V startup path relies on ACPI to detect running under a Hyper-V compatible hypervisor. That doesn't work on non-ACPI systems. Hoist the ACPI detection logic into a separate function. Then use the vendor-specific hypervisor service call (implemented recently in Hyper-V) via SMCCC in the non-ACPI case. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> --- arch/arm64/hyperv/mshyperv.c | 43 +++++++++++++++++++++++++++++++----- 1 file changed, 38 insertions(+), 5 deletions(-)