From 1f365bb0de12da4a9ef8e56ffba2218d9a026011 Mon Sep 17 00:00:00 2001 From: Aneesh Kumar K.V Date: Tue, 6 May 2014 23:31:36 +0530 Subject: KVM: PPC: BOOK3S: HV: Add mixed page-size support for guest On recent IBM Power CPUs, while the hashed page table is looked up using the page size from the segmentation hardware (i.e. the SLB), it is possible to have the HPT entry indicate a larger page size. Thus for example it is possible to put a 16MB page in a 64kB segment, but since the hash lookup is done using a 64kB page size, it may be necessary to put multiple entries in the HPT for a single 16MB page. This capability is called mixed page-size segment (MPSS). With MPSS, there are two relevant page sizes: the base page size, which is the size used in searching the HPT, and the actual page size, which is the size indicated in the HPT entry. [ Note that the actual page size is always >= base page size ]. We use "ibm,segment-page-sizes" device tree node to advertise the MPSS support to PAPR guest. The penc encoding indicates whether we support a specific combination of base page size and actual page size in the same segment. We also use the penc value in the LP encoding of HPTE entry. This patch exposes MPSS support to KVM guest by advertising the feature via "ibm,segment-page-sizes". It also adds the necessary changes to decode the base page size and the actual page size correctly from the HPTE entry. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Alexander Graf --- arch/powerpc/kvm/book3s_hv.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/powerpc/kvm') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 3a9456165224..aba05bbb3e74 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1930,6 +1930,13 @@ static void kvmppc_add_seg_page_size(struct kvm_ppc_one_seg_page_size **sps, * support pte_enc here */ (*sps)->enc[0].pte_enc = def->penc[linux_psize]; + /* + * Add 16MB MPSS support if host supports it + */ + if (linux_psize != MMU_PAGE_16M && def->penc[MMU_PAGE_16M] != -1) { + (*sps)->enc[1].page_shift = 24; + (*sps)->enc[1].pte_enc = def->penc[MMU_PAGE_16M]; + } (*sps)++; } -- cgit v1.2.3