0666703c4b
commit cdaa0a407f1acd3a44861e3aea6e3c7349e668f1 upstream.
When running identity-mapped and depending on the kernel configuration,
it is possible that the compiler uses jump tables when generating code
for cc_platform_has().
This causes a boot failure because the jump table uses un-mapped kernel
virtual addresses, not identity-mapped addresses. This has been seen
with CONFIG_RETPOLINE=n.
Similar to sme_encrypt_kernel(), use an open-coded direct check for the
status of SNP rather than trying to eliminate the jump table. This
preserves any code optimization in cc_platform_has() that can be useful
post boot. It also limits the changes to SEV-specific files so that
future compiler features won't necessarily require possible build changes
just because they are not compatible with running identity-mapped.
[ bp: Massage commit message. ]
Fixes: 5e5ccff60a29 ("x86/sev: Add helper for validating pages in early enc attribute changes")
Reported-by: Sean Christopherson <seanjc@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 5.19.x
Link: https://lore.kernel.org/all/YqfabnTRxFSM+LoX@google.com/
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.