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Linux kernel source tree
22836e1de6
Handle TLB tracking for TDX by introducing function tdx_track() for private memory TLB tracking and implementing flush_tlb* hooks to flush TLBs for shared memory. Introduce function tdx_track() to do TLB tracking on private memory, which basically does two things: calling TDH.MEM.TRACK to increase TD epoch and kicking off all vCPUs. The private EPT will then be flushed when each vCPU re-enters the TD. This function is unused temporarily in this patch and will be called on a page-by-page basis on removal of private guest page in a later patch. In earlier revisions, tdx_track() relied on an atomic counter to coordinate the synchronization between the actions of kicking off vCPUs, incrementing the TD epoch, and the vCPUs waiting for the incremented TD epoch after being kicked off. However, the core MMU only actually needs to call tdx_track() while aleady under a write mmu_lock. So this sychnonization can be made to be unneeded. vCPUs are kicked off only after the successful execution of TDH.MEM.TRACK, eliminating the need for vCPUs to wait for TDH.MEM.TRACK completion after being kicked off. tdx_track() is therefore able to send requests KVM_REQ_OUTSIDE_GUEST_MODE rather than KVM_REQ_TLB_FLUSH. Hooks for flush_remote_tlb and flush_remote_tlbs_range are not necessary for TDX, as tdx_track() will handle TLB tracking of private memory on page-by-page basis when private guest pages are removed. There is no need to invoke tdx_track() again in kvm_flush_remote_tlbs() even after changes to the mirrored page table. For hooks flush_tlb_current and flush_tlb_all, which are invoked during kvm_mmu_load() and vcpu load for normal VMs, let VMM to flush all EPTs in the two hooks for simplicity, since TDX does not depend on the two hooks to notify TDX module to flush private EPT in those cases. Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Co-developed-by: Yan Zhao <yan.y.zhao@intel.com> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com> Message-ID: <20241112073753.22228-1-yan.y.zhao@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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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 reStructuredText 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.