Messages in this thread Patch in this message | | | From | Balbir Singh <> | Subject | [PATCH v6 1/6] arch/x86/kvm: Refactor l1d flush lifecycle management | Date | Sun, 10 May 2020 11:47:58 +1000 |
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Split out the allocation and free routines to be used in a follow up set of patches (to reuse for L1D flushing).
Signed-off-by: Balbir Singh <sblbir@amazon.com> Reviewed-by: Kees Cook <keescook@chromium.org> --- arch/x86/include/asm/cacheflush.h | 3 +++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/l1d_flush.c | 36 +++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 25 +++------------------ 4 files changed, 43 insertions(+), 22 deletions(-) create mode 100644 arch/x86/kernel/l1d_flush.c
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h index 63feaf2a5f93..bac56fcd9790 100644 --- a/arch/x86/include/asm/cacheflush.h +++ b/arch/x86/include/asm/cacheflush.h @@ -6,6 +6,9 @@ #include <asm-generic/cacheflush.h> #include <asm/special_insns.h> +#define L1D_CACHE_ORDER 4 void clflush_cache_range(void *addr, unsigned int size); +void *l1d_flush_alloc_pages(void); +void l1d_flush_cleanup_pages(void *l1d_flush_pages); #endif /* _ASM_X86_CACHEFLUSH_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index e77261db2391..c17c1e3c1a0b 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -157,3 +157,4 @@ ifeq ($(CONFIG_X86_64),y) endif obj-$(CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT) += ima_arch.o +obj-y += l1d_flush.o diff --git a/arch/x86/kernel/l1d_flush.c b/arch/x86/kernel/l1d_flush.c new file mode 100644 index 000000000000..d605878c8f28 --- /dev/null +++ b/arch/x86/kernel/l1d_flush.c @@ -0,0 +1,36 @@ +#include <linux/mm.h> +#include <asm/cacheflush.h> + +void *l1d_flush_alloc_pages(void) +{ + struct page *page; + void *l1d_flush_pages = NULL; + int i; + + /* + * This allocation for l1d_flush_pages is not tied to a VM/task's + * lifetime and so should not be charged to a memcg. + */ + page = alloc_pages(GFP_KERNEL, L1D_CACHE_ORDER); + if (!page) + return NULL; + l1d_flush_pages = page_address(page); + + /* + * Initialize each page with a different pattern in + * order to protect against KSM in the nested + * virtualization case. + */ + for (i = 0; i < 1u << L1D_CACHE_ORDER; ++i) { + memset(l1d_flush_pages + i * PAGE_SIZE, i + 1, + PAGE_SIZE); + } + return l1d_flush_pages; +} +EXPORT_SYMBOL_GPL(l1d_flush_alloc_pages); + +void l1d_flush_cleanup_pages(void *l1d_flush_pages) +{ + free_pages((unsigned long)l1d_flush_pages, L1D_CACHE_ORDER); +} +EXPORT_SYMBOL_GPL(l1d_flush_cleanup_pages); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 00d31a5e0089..f35654db904a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -203,14 +203,10 @@ static const struct { [VMENTER_L1D_FLUSH_NOT_REQUIRED] = {"not required", false}, }; -#define L1D_CACHE_ORDER 4 static void *vmx_l1d_flush_pages; static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) { - struct page *page; - unsigned int i; - if (!boot_cpu_has_bug(X86_BUG_L1TF)) { l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED; return 0; @@ -253,24 +249,9 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) if (l1tf != VMENTER_L1D_FLUSH_NEVER && !vmx_l1d_flush_pages && !boot_cpu_has(X86_FEATURE_FLUSH_L1D)) { - /* - * This allocation for vmx_l1d_flush_pages is not tied to a VM - * lifetime and so should not be charged to a memcg. - */ - page = alloc_pages(GFP_KERNEL, L1D_CACHE_ORDER); - if (!page) + vmx_l1d_flush_pages = l1d_flush_alloc_pages(); + if (!vmx_l1d_flush_pages) return -ENOMEM; - vmx_l1d_flush_pages = page_address(page); - - /* - * Initialize each page with a different pattern in - * order to protect against KSM in the nested - * virtualization case. - */ - for (i = 0; i < 1u << L1D_CACHE_ORDER; ++i) { - memset(vmx_l1d_flush_pages + i * PAGE_SIZE, i + 1, - PAGE_SIZE); - } } l1tf_vmx_mitigation = l1tf; @@ -8099,7 +8080,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = { static void vmx_cleanup_l1d_flush(void) { if (vmx_l1d_flush_pages) { - free_pages((unsigned long)vmx_l1d_flush_pages, L1D_CACHE_ORDER); + l1d_flush_cleanup_pages(vmx_l1d_flush_pages); vmx_l1d_flush_pages = NULL; } /* Restore state so sysfs ignores VMX */ -- 2.17.1
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