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Thus at this > > + * moment we can expect that the device will not generate ATS queries > > + * and so we don't care about the sequencing of EATS. The purpose of > > + * EATS is to protect the system from hostile untrusted devices that > > + * issue ATS when the PCI config space is disabled. However, if EATS > > + * is being changed then we already must be trusting the device since > > + * the EATS security block is being disabled. > > + * > > + * Note: Since we moved the EATS update to the first phase, changing > > + * S2S and EATS might transiently set S2S=1 and EATS=1, resulting in > > + * a bad STE. See "5.2 Stream Table Entry". In such a case, we can't > > + * do a hitless update. > > + */ > > + if (!((cur[2] | target[2]) & cpu_to_le64(STRTAB_STE_2_S2S))) > > + safe_bits[1] |= cpu_to_le64(STRTAB_STE_1_EATS); > > I understand what we're trying to do here but isn't this implicitly > saying it is safe to transition hitlessly to any non-zero EATS value, > including S1CHK or RSVD. S1CHK might have other config dependencies? Will pointed this issue with S1CHK, Nicolin has a suggestion to fix it here: https://lore.kernel.org/linux-iommu/aWarF90zBqxD0Gef@Asurada-Nvidia/ It would block RSVD too. Thanks, Jason