From bd104e6db6f0ad124e507a9ecf1a468efe5697db Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Mon, 19 Aug 2019 23:13:18 -0300 Subject: [PATCH] powerpc/pseries/svm: Use shared memory for LPPACA structures LPPACA structures need to be shared with the host. Hence they need to be in shared memory. Instead of allocating individual chunks of memory for a given structure from memblock, a contiguous chunk of memory is allocated and then converted into shared memory. Subsequent allocation requests will come from the contiguous chunk which will be always shared memory for all structures. While we are able to use a kmem_cache constructor for the Debug Trace Log, LPPACAs are allocated very early in the boot process (before SLUB is available) so we need to use a simpler scheme here. Introduce helper is_svm_platform() which uses the S bit of the MSR to tell whether we're running as a secure guest. Signed-off-by: Anshuman Khandual Signed-off-by: Thiago Jung Bauermann Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190820021326.6884-9-bauerman@linux.ibm.com --- arch/powerpc/include/asm/svm.h | 26 ++++++++++++++++++++ arch/powerpc/kernel/paca.c | 43 +++++++++++++++++++++++++++++++++- 2 files changed, 68 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/include/asm/svm.h diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h new file mode 100644 index 000000000000..2689d8d841f8 --- /dev/null +++ b/arch/powerpc/include/asm/svm.h @@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * SVM helper functions + * + * Copyright 2018 Anshuman Khandual, IBM Corporation. + */ + +#ifndef _ASM_POWERPC_SVM_H +#define _ASM_POWERPC_SVM_H + +#ifdef CONFIG_PPC_SVM + +static inline bool is_secure_guest(void) +{ + return mfmsr() & MSR_S; +} + +#else /* CONFIG_PPC_SVM */ + +static inline bool is_secure_guest(void) +{ + return false; +} + +#endif /* CONFIG_PPC_SVM */ +#endif /* _ASM_POWERPC_SVM_H */ diff --git a/arch/powerpc/kernel/paca.c b/arch/powerpc/kernel/paca.c index 612fc87ef785..949eceb254d8 100644 --- a/arch/powerpc/kernel/paca.c +++ b/arch/powerpc/kernel/paca.c @@ -14,6 +14,8 @@ #include #include #include +#include +#include #include "setup.h" @@ -54,6 +56,41 @@ static void *__init alloc_paca_data(unsigned long size, unsigned long align, #define LPPACA_SIZE 0x400 +static void *__init alloc_shared_lppaca(unsigned long size, unsigned long align, + unsigned long limit, int cpu) +{ + size_t shared_lppaca_total_size = PAGE_ALIGN(nr_cpu_ids * LPPACA_SIZE); + static unsigned long shared_lppaca_size; + static void *shared_lppaca; + void *ptr; + + if (!shared_lppaca) { + memblock_set_bottom_up(true); + + shared_lppaca = + memblock_alloc_try_nid(shared_lppaca_total_size, + PAGE_SIZE, MEMBLOCK_LOW_LIMIT, + limit, NUMA_NO_NODE); + if (!shared_lppaca) + panic("cannot allocate shared data"); + + memblock_set_bottom_up(false); + uv_share_page(PHYS_PFN(__pa(shared_lppaca)), + shared_lppaca_total_size >> PAGE_SHIFT); + } + + ptr = shared_lppaca + shared_lppaca_size; + shared_lppaca_size += size; + + /* + * This is very early in boot, so no harm done if the kernel crashes at + * this point. + */ + BUG_ON(shared_lppaca_size >= shared_lppaca_total_size); + + return ptr; +} + /* * See asm/lppaca.h for more detail. * @@ -83,7 +120,11 @@ static struct lppaca * __init new_lppaca(int cpu, unsigned long limit) if (early_cpu_has_feature(CPU_FTR_HVMODE)) return NULL; - lp = alloc_paca_data(LPPACA_SIZE, 0x400, limit, cpu); + if (is_secure_guest()) + lp = alloc_shared_lppaca(LPPACA_SIZE, 0x400, limit, cpu); + else + lp = alloc_paca_data(LPPACA_SIZE, 0x400, limit, cpu); + init_lppaca(lp); return lp;