bhyve: add ioctl to modify the second level address translation
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Authored by corvink on Nov 29 2021, 10:36 AM.

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manu
markj
jhb

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bhyve

Summary

Second level address translation is used to create a mapping between
guest addresses and host addresses. In order to allow passthru of
mmio devices like a TPM, we need to modify the SLAT. Therefore,
add an ioctl for several modifications of the SLAT.

Note: You can take a look at https://github.com/Beckhoff/freebsd-src/commits/phab/corvink/vm_modify_slat

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rG FreeBSD src repository

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Event Timeline

corvink created this revision.Nov 29 2021, 10:36 AM

Herald added subscribers: bcran, rgrimes, imp. · View Herald TranscriptNov 29 2021, 10:36 AM

corvink requested review of this revision.Nov 29 2021, 10:36 AM

markj added inline comments.Nov 29 2021, 5:47 PM

lib/libvmmapi/vmmapi.h
190	Whitespace is inconsistent.
sys/amd64/vmm/vmm.c
649	This functions return Mach error numbers, for legacy reasons. They need to be translated to errno values before a return to user mode. See vm_mmap_memseg() for an example.
sys/amd64/vmm/vmm_dev.c
550	There is no validation that the HPA actually corresponds to a SLAT...?

corvink added inline comments.Nov 30 2021, 8:54 AM

sys/amd64/vmm/vmm_dev.c
550	HPA isn't part of the SLAT. `vm_map_mmio` should add it to EPT.

corvink mentioned this in D26209: GVT-d support for bhyve.Dec 2 2021, 11:19 AM

This patch was required for my TPM passthrough patch (D32961). I'll change the TPM passthrough patch in the future. After that, this patch won't be required any more.