Randy Dunlap
2021-Oct-09 01:45 UTC
[PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared
On 10/8/21 5:37 PM, Kuppuswamy Sathyanarayanan wrote:> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 91ba391f9b32..0af19cb1a28c 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2076,6 +2076,18 @@ > 1 - Bypass the IOMMU for DMA. > unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. > > + ioremap_force_shared= [X86_64, CCG] > + Force the kernel to use shared memory mappings which do > + not use ioremap_host_shared/pcimap_host_shared to opt-in > + to shared mappings with the host. This feature is mainly > + used by a confidential guest when enabling new drivers > + without proper shared memory related changes. Please note > + that this option might also allow other non explicitly > + enabled drivers to interact with the host in confidential > + guest, which could cause other security risks. This option > + will also cause BIOS data structures to be shared with the > + host, which might open security holes.Hi, This cmdline option text should have a little bit more info. Just as an example/template: acpi_apic_instance= [ACPI, IOAPIC] Format: <int> 2: use 2nd APIC table, if available 1,0: use 1st APIC table default: 0 So what is expected after the "=" sign?... thanks. -- ~Randy