Doc: admin-guide: Add entry for kvm_cma_resv_ratio kernel param

Add document entry for kvm_cma_resv_ratio kernel param which
is used to alter the KVM contiguous memory allocation percentage
for hash pagetable allocation used by hash mode PowerPC KVM guests.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20200921090220.14981-1-sathnaga@linux.vnet.ibm.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d81d1d8..b1e3d63 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2261,6 +2261,14 @@
                        [KVM,ARM] Allow use of GICv4 for direct injection of
                        LPIs.
 
+       kvm_cma_resv_ratio=n [PPC]
+                       Reserves given percentage from system memory area for
+                       contiguous memory allocation for KVM hash pagetable
+                       allocation.
+                       By default it reserves 5% of total system memory.
+                       Format: <integer>
+                       Default: 5
+
        kvm-intel.ept=  [KVM,Intel] Disable extended page tables
                        (virtualized MMU) support on capable Intel chips.
                        Default is 1 (enabled)