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Message-ID: <20200510014803.12190-2-sblbir@amazon.com>
Date: Sun, 10 May 2020 11:47:58 +1000
From: Balbir Singh <sblbir@...zon.com>
To: <tglx@...utronix.de>, <linux-kernel@...r.kernel.org>
CC: <jpoimboe@...hat.com>, <tony.luck@...el.com>,
<keescook@...omium.org>, <benh@...nel.crashing.org>,
<x86@...nel.org>, <dave.hansen@...el.com>,
<thomas.lendacky@....com>, Balbir Singh <sblbir@...zon.com>
Subject: [PATCH v6 1/6] arch/x86/kvm: Refactor l1d flush lifecycle management
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@...zon.com>
Reviewed-by: Kees Cook <keescook@...omium.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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