From d0e1ca1045849f6aa71491b7ca9566cbdd94a32c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 13 Jul 2018 16:23:19 +0200 Subject: [PATCH] x86/kvm: Move l1tf setup function commit 7db92e165ac814487264632ab2624e832f20ae38 upstream In preparation of allowing run time control for L1D flushing, move the setup code to the module parameter handler. In case of pre module init parsing, just store the value and let vmx_init() do the actual setup after running kvm_init() so that enable_ept is having the correct state. During run-time invoke it directly from the parameter setter to prepare for run-time control. Signed-off-by: Thomas Gleixner Tested-by: Jiri Kosina Reviewed-by: Greg Kroah-Hartman Reviewed-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20180713142322.694063239@linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx.c | 123 ++++++++++++++++++++++++++++----------------- 1 file changed, 77 insertions(+), 46 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 8ddc6b794a94..98fa2911bd33 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -196,7 +196,8 @@ extern const ulong vmx_return; static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush); -static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush = VMENTER_L1D_FLUSH_COND; +/* Storage for pre module init parameter parsing */ +static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush_param = VMENTER_L1D_FLUSH_AUTO; static const struct { const char *option; @@ -208,33 +209,85 @@ static const struct { {"always", VMENTER_L1D_FLUSH_ALWAYS}, }; -static int vmentry_l1d_flush_set(const char *s, const struct kernel_param *kp) +#define L1D_CACHE_ORDER 4 +static void *vmx_l1d_flush_pages; + +static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) { - unsigned int i; + struct page *page; - if (!s) - return -EINVAL; + /* If set to 'auto' select 'cond' */ + if (l1tf == VMENTER_L1D_FLUSH_AUTO) + l1tf = VMENTER_L1D_FLUSH_COND; - for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) { - if (!strcmp(s, vmentry_l1d_param[i].option)) { - vmentry_l1d_flush = vmentry_l1d_param[i].cmd; - return 0; - } + if (!enable_ept) { + l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_EPT_DISABLED; + return 0; + } + + if (l1tf != VMENTER_L1D_FLUSH_NEVER && !vmx_l1d_flush_pages && + !boot_cpu_has(X86_FEATURE_FLUSH_L1D)) { + page = alloc_pages(GFP_KERNEL, L1D_CACHE_ORDER); + if (!page) + return -ENOMEM; + vmx_l1d_flush_pages = page_address(page); } + l1tf_vmx_mitigation = l1tf; + + if (l1tf != VMENTER_L1D_FLUSH_NEVER) + static_branch_enable(&vmx_l1d_should_flush); + return 0; +} + +static int vmentry_l1d_flush_parse(const char *s) +{ + unsigned int i; + + if (s) { + for (i = 0; i < ARRAY_SIZE(vmentry_l1d_param); i++) { + if (!strcmp(s, vmentry_l1d_param[i].option)) + return vmentry_l1d_param[i].cmd; + } + } return -EINVAL; } +static int vmentry_l1d_flush_set(const char *s, const struct kernel_param *kp) +{ + int l1tf; + + if (!boot_cpu_has(X86_BUG_L1TF)) + return 0; + + l1tf = vmentry_l1d_flush_parse(s); + if (l1tf < 0) + return l1tf; + + /* + * Has vmx_init() run already? If not then this is the pre init + * parameter parsing. In that case just store the value and let + * vmx_init() do the proper setup after enable_ept has been + * established. + */ + if (l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_AUTO) { + vmentry_l1d_flush_param = l1tf; + return 0; + } + + return vmx_setup_l1d_flush(l1tf); +} + static int vmentry_l1d_flush_get(char *s, const struct kernel_param *kp) { - return sprintf(s, "%s\n", vmentry_l1d_param[vmentry_l1d_flush].option); + return sprintf(s, "%s\n", vmentry_l1d_param[l1tf_vmx_mitigation].option); } static const struct kernel_param_ops vmentry_l1d_flush_ops = { .set = vmentry_l1d_flush_set, .get = vmentry_l1d_flush_get, }; -module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, &vmentry_l1d_flush, S_IRUGO); +module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, S_IRUGO); #define NR_AUTOLOAD_MSRS 8 @@ -9083,7 +9136,7 @@ static void vmx_l1d_flush(struct kvm_vcpu *vcpu) * it. The flush bit gets set again either from vcpu_run() or from * one of the unsafe VMEXIT handlers. */ - always = vmentry_l1d_flush == VMENTER_L1D_FLUSH_ALWAYS; + always = l1tf_vmx_mitigation == VMENTER_L1D_FLUSH_ALWAYS; vcpu->arch.l1tf_flush_l1d = always; vcpu->stat.l1d_flush++; @@ -12495,34 +12548,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = { .setup_mce = vmx_setup_mce, }; -static int __init vmx_setup_l1d_flush(void) -{ - struct page *page; - - if (!boot_cpu_has_bug(X86_BUG_L1TF)) - return 0; - - if (!enable_ept) { - l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_EPT_DISABLED; - return 0; - } - - l1tf_vmx_mitigation = vmentry_l1d_flush; - - if (vmentry_l1d_flush == VMENTER_L1D_FLUSH_NEVER) - return 0; - - if (!boot_cpu_has(X86_FEATURE_FLUSH_L1D)) { - page = alloc_pages(GFP_KERNEL, L1D_CACHE_ORDER); - if (!page) - return -ENOMEM; - vmx_l1d_flush_pages = page_address(page); - } - - static_branch_enable(&vmx_l1d_should_flush); - return 0; -} - static void vmx_cleanup_l1d_flush(void) { if (vmx_l1d_flush_pages) { @@ -12557,12 +12582,18 @@ static int __init vmx_init(void) return r; /* - * Must be called after kvm_init() so enable_ept is properly set up + * Must be called after kvm_init() so enable_ept is properly set + * up. Hand the parameter mitigation value in which was stored in + * the pre module init parser. If no parameter was given, it will + * contain 'auto' which will be turned into the default 'cond' + * mitigation mode. */ - r = vmx_setup_l1d_flush(); - if (r) { - vmx_exit(); - return r; + if (boot_cpu_has(X86_BUG_L1TF)) { + r = vmx_setup_l1d_flush(vmentry_l1d_flush_param); + if (r) { + vmx_exit(); + return r; + } } #ifdef CONFIG_KEXEC_CORE -- 2.20.1