From bf6b7661f41615c0815fce0a3f27acb5fc005470 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Mon, 27 Jul 2020 14:29:08 +0530 Subject: powerpc/book3s64/radix: Add kernel command line option to disable radix GTSE This adds a kernel command line option that can be used to disable GTSE support. Disabling GTSE implies kernel will make hcalls to invalidate TLB entries. This was done so that we can do VM migration between configs that enable/disable GTSE support via hypervisor. To migrate a VM from a system that supports GTSE to a system that doesn't, we can boot the guest with radix_hcall_invalidate=on, thereby forcing the guest to use hcalls for TLB invalidates. The check for hcall availability is done in pSeries_setup_arch so that the panic message appears on the console. This should only happen on a hypervisor that doesn't force the guest to hash translation even though it can't handle the radix GTSE=0 request via CAS. With radix_hcall_invalidate=on if the hypervisor doesn't support hcall_rpt_invalidate hcall it should force the LPAR to hash translation. Signed-off-by: Aneesh Kumar K.V Tested-by: Bharata B Rao Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200727085908.420806-1-aneesh.kumar@linux.ibm.com --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'Documentation/admin-guide/kernel-parameters.txt') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb95fad81c79..3ab61cd0f89c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -896,6 +896,10 @@ disable_radix [PPC] Disable RADIX MMU mode on POWER9 + radix_hcall_invalidate=on [PPC/PSERIES] + Disable RADIX GTSE feature and use hcall for TLB + invalidate. + disable_tlbie [PPC] Disable TLBIE instruction. Currently does not work with KVM, with HASH MMU, or with coherent accelerators. -- cgit v1.2.3