Disallow MSR read/writes#991
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Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>
Add an MSHV-only probe that checks whether a host write of HV_X64_REGISTER_TSC resets a guest-shifted TSC, deciding if the raw-TSC leak can be closed by reset. Broaden the test-only MSR helpers to MSHV. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>
Reset the raw TSC (0x10) on every backend. Hyper-V models TSC and TSC_ADJUST as independent registers, so a guest WRMSR(TSC) is not folded into TSC_ADJUST and resetting TSC_ADJUST alone leaves the shift in place. Deny is not possible on the filterless backends because Hyper-V refuses a root MSR intercept for an implemented MSR, so reset is the only lever. Add TSC to the KVM reset core too, purely for cross-backend consistency, so a restore rewinds the guest clock uniformly. The KVM filter still denies guest TSC writes, so nothing leaks there. Document the full rationale in docs/msr.md. Signed-off-by: Ludvig Liljenberg <4257730+ludfjig@users.noreply.github.com>
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Disallows reading/writing MSRs in the guest. The goal is to prevent guest state to persist across snapshot-restores.
Will mark ready for review once KVM releases new version, which should include newly added
KVM_X86_SET_MSR_FILTERvm ioctl that this PR depends on, see rust-vmm/kvm#359