MsvmPkg/PlatformPei: Skip DMA pinning detection when Hv is disabled#95
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jstarks merged 1 commit intoJul 21, 2026
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HvDetectDmaPinningRequired() issues an AArch64 hypercall (AsmGetVpRegister(HvRegisterFeaturesInfo)) unconditionally during PEI. The X64 path guards this with a HypervisorPresent CPUID check, but the AArch64 path had no equivalent guard. On a Generic (no-Hyper-V) platform there is no hypervisor to service the hvc. Issuing it in PEI - before the exception vectors are installed - causes an intercept loop that hard hangs the machine. This is a regression: the no-Hv support (PcdHvEnabled, gated via the SEC platform type PPI) predates HvDetectDmaPinningRequired, which was added later by the IommuDxe pinning work without accounting for the no-Hv path. Guard the whole detection on PcdHvEnabled so no hypercall is issued when Hyper-V is disabled. X64 is unaffected (PcdHvEnabled defaults TRUE and is never cleared there).
maheeraeron
approved these changes
Jul 20, 2026
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HvDetectDmaPinningRequired() issues an AArch64 hypercall (AsmGetVpRegister(HvRegisterFeaturesInfo)) unconditionally during PEI. The X64 path guards this with a HypervisorPresent CPUID check, but the AArch64 path had no equivalent guard.
On a Generic (no-Hyper-V) platform there is no hypervisor to service the hvc. Issuing it in PEI - before the exception vectors are installed - causes an intercept loop that hard hangs the machine.
This is a regression: the no-Hv support (PcdHvEnabled, gated via the SEC platform type PPI) predates HvDetectDmaPinningRequired, which was added later by the IommuDxe pinning work without accounting for the no-Hv path.
Guard the whole detection on PcdHvEnabled so no hypercall is issued when Hyper-V is disabled. X64 is unaffected (PcdHvEnabled defaults TRUE and is never cleared there).