Re: [PATCH v4 09/14] KVM: arm64: Pass walk flags to kvm_pgtable_get_leaf()

[sashiko-bot@kernel.org]

> From: Jack Thomson <jackabt@amazon.com>
> 
> Allow callers of kvm_pgtable_get_leaf() to specify the page-table walk
> flags, in preparation for performing walks under the MMU read lock.
> 
> Reading a stage-2 leaf while only holding the read lock requires
> KVM_PGTABLE_WALK_SHARED: parallel faults (which also only hold the read
> lock) can unlink table pages and free them via RCU, so the walker must
> be inside an RCU read-side critical section, which the shared walk flag
> provides via kvm_pgtable_walk_begin().
> 
> All existing callers either hold the write lock, walk with interrupts
> disabled, or run at hyp where shared walks are rejected; they keep the
> current behaviour by passing no flags.
> 
> No functional change intended.
> 
> Signed-off-by: Jack Thomson <jackabt@amazon.com>
> [ljs: fixup new kvm_pgtable_get_leaf() invocation]
> Reviewed-by: Oliver Upton <oupton@kernel.org>
> Reviewed-by: Fuad Tabba <fuad.tabba@linux.dev>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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