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Message-ID: <20200423140125.7332-5-sblbir@amazon.com>
Date: Fri, 24 Apr 2020 00:01:23 +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>,
"Balbir Singh" <sblbir@...zon.com>
Subject: [PATCH v4 4/6] arch/x86/kvm: Refactor L1D flushing
Move out the initialization function to l1d_flush_init_once()
so that it can be reused for subsequent patches. The side-effect
of this patch is that the memory allocated for l1d flush pages
is no longer freed up and the memory allocated once is shared
amongst callers.
l1d_flush_sw/hw() are now abstracted under arch_l1d_flush().
vmx_l1d_flush_mutex however continues to exist as it also used
from other code paths.
Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Balbir Singh <sblbir@...zon.com>
---
arch/x86/include/asm/cacheflush.h | 12 ++++---
arch/x86/kernel/l1d_flush.c | 53 +++++++++++++++++++++++--------
arch/x86/kvm/vmx/vmx.c | 20 ++----------
3 files changed, 50 insertions(+), 35 deletions(-)
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index 21cc3b28fa63..851d8f1ab827 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -7,11 +7,13 @@
#include <asm/special_insns.h>
#define L1D_CACHE_ORDER 4
+
+enum l1d_flush_options {
+ L1D_FLUSH_POPULATE_TLB = 0x1,
+};
+
void clflush_cache_range(void *addr, unsigned int size);
-void l1d_flush_populate_tlb(void *l1d_flush_pages);
-void *l1d_flush_alloc_pages(void);
-void l1d_flush_cleanup_pages(void *l1d_flush_pages);
-void l1d_flush_sw(void *l1d_flush_pages);
-int l1d_flush_hw(void);
+int l1d_flush_init_once(void);
+void arch_l1d_flush(enum l1d_flush_options options);
#endif /* _ASM_X86_CACHEFLUSH_H */
diff --git a/arch/x86/kernel/l1d_flush.c b/arch/x86/kernel/l1d_flush.c
index 5871794f890d..a754b6c288a9 100644
--- a/arch/x86/kernel/l1d_flush.c
+++ b/arch/x86/kernel/l1d_flush.c
@@ -1,7 +1,7 @@
#include <linux/mm.h>
#include <asm/cacheflush.h>
-void *l1d_flush_alloc_pages(void)
+static void *l1d_flush_alloc_pages(void)
{
struct page *page;
void *l1d_flush_pages = NULL;
@@ -27,20 +27,14 @@ void *l1d_flush_alloc_pages(void)
}
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);
/*
* Not all users of l1d flush would want to populate the TLB first
* split out the function so that callers can optionally flush the L1D
* cache via sw without prefetching the TLB.
*/
-void l1d_flush_populate_tlb(void *l1d_flush_pages)
+static void l1d_flush_populate_tlb(void *l1d_flush_pages)
{
int size = PAGE_SIZE << L1D_CACHE_ORDER;
@@ -58,9 +52,8 @@ void l1d_flush_populate_tlb(void *l1d_flush_pages)
[size] "r" (size)
: "eax", "ebx", "ecx", "edx");
}
-EXPORT_SYMBOL_GPL(l1d_flush_populate_tlb);
-int l1d_flush_hw(void)
+static int l1d_flush_hw(void)
{
if (static_cpu_has(X86_FEATURE_FLUSH_L1D)) {
wrmsrl(MSR_IA32_FLUSH_CMD, L1D_FLUSH);
@@ -68,9 +61,8 @@ int l1d_flush_hw(void)
}
return -ENOTSUPP;
}
-EXPORT_SYMBOL_GPL(l1d_flush_hw);
-void l1d_flush_sw(void *l1d_flush_pages)
+static void l1d_flush_sw(void *l1d_flush_pages)
{
int size = PAGE_SIZE << L1D_CACHE_ORDER;
@@ -87,4 +79,39 @@ void l1d_flush_sw(void *l1d_flush_pages)
[size] "r" (size)
: "eax", "ecx");
}
-EXPORT_SYMBOL_GPL(l1d_flush_sw);
+
+static void *l1d_flush_pages;
+static DEFINE_MUTEX(l1d_flush_mutex);
+
+/*
+ * Initialize and setup L1D flush once, each caller will reuse the
+ * l1d_flush_pages for flushing, no per CPU allocations or NUMA aware
+ * allocations at the moment.
+ */
+int l1d_flush_init_once(void)
+{
+ int ret = 0;
+
+ if (static_cpu_has(X86_FEATURE_FLUSH_L1D) || l1d_flush_pages)
+ return ret;
+
+ mutex_lock(&l1d_flush_mutex);
+ if (!l1d_flush_pages)
+ l1d_flush_pages = l1d_flush_alloc_pages();
+ ret = l1d_flush_pages ? 0 : -ENOMEM;
+ mutex_unlock(&l1d_flush_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(l1d_flush_init_once);
+
+void arch_l1d_flush(enum l1d_flush_options options)
+{
+ if (!l1d_flush_hw())
+ return;
+
+ if (options & L1D_FLUSH_POPULATE_TLB)
+ l1d_flush_populate_tlb(l1d_flush_pages);
+
+ l1d_flush_sw(l1d_flush_pages);
+}
+EXPORT_SYMBOL_GPL(arch_l1d_flush);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 786d1615a09f..d489234c4d5a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -203,8 +203,6 @@ static const struct {
[VMENTER_L1D_FLUSH_NOT_REQUIRED] = {"not required", false},
};
-static void *vmx_l1d_flush_pages;
-
static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
{
if (!boot_cpu_has_bug(X86_BUG_L1TF)) {
@@ -247,12 +245,9 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
l1tf = VMENTER_L1D_FLUSH_ALWAYS;
}
- if (l1tf != VMENTER_L1D_FLUSH_NEVER && !vmx_l1d_flush_pages &&
- !boot_cpu_has(X86_FEATURE_FLUSH_L1D)) {
- vmx_l1d_flush_pages = l1d_flush_alloc_pages();
- if (!vmx_l1d_flush_pages)
+ if (l1tf != VMENTER_L1D_FLUSH_NEVER)
+ if (l1d_flush_init_once())
return -ENOMEM;
- }
l1tf_vmx_mitigation = l1tf;
@@ -6010,12 +6005,7 @@ static void vmx_l1d_flush(struct kvm_vcpu *vcpu)
}
vcpu->stat.l1d_flush++;
-
- if (!l1d_flush_hw())
- return;
-
- l1d_flush_populate_tlb(vmx_l1d_flush_pages);
- l1d_flush_sw(vmx_l1d_flush_pages);
+ arch_l1d_flush(L1D_FLUSH_POPULATE_TLB);
}
static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
@@ -7983,10 +7973,6 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
static void vmx_cleanup_l1d_flush(void)
{
- if (vmx_l1d_flush_pages) {
- l1d_flush_cleanup_pages(vmx_l1d_flush_pages);
- vmx_l1d_flush_pages = NULL;
- }
/* Restore state so sysfs ignores VMX */
l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
}
--
2.17.1
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