From 51789f25c833b37f879554020f11af0a3a72076f Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 7 Sep 2023 12:25:51 +0100 Subject: [PATCH] 6.4-stable patches added patches: kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch --- ...ow-sticky-disabling-of-nx_huge_pages.patch | 132 ++++++++++++++++++ queue-6.4/series | 1 + 2 files changed, 133 insertions(+) create mode 100644 queue-6.4/kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch diff --git a/queue-6.4/kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch b/queue-6.4/kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch new file mode 100644 index 00000000000..b4a82215619 --- /dev/null +++ b/queue-6.4/kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch @@ -0,0 +1,132 @@ +From 0b210faf337314e4bc88e796218bc70c72a51209 Mon Sep 17 00:00:00 2001 +From: Sean Christopherson +Date: Thu, 1 Jun 2023 17:58:59 -0700 +Subject: KVM: x86/mmu: Add "never" option to allow sticky disabling of nx_huge_pages + +From: Sean Christopherson + +commit 0b210faf337314e4bc88e796218bc70c72a51209 upstream. + +Add a "never" option to the nx_huge_pages module param to allow userspace +to do a one-way hard disabling of the mitigation, and don't create the +per-VM recovery threads when the mitigation is hard disabled. Letting +userspace pinky swear that userspace doesn't want to enable NX mitigation +(without reloading KVM) allows certain use cases to avoid the latency +problems associated with spawning a kthread for each VM. + +E.g. in FaaS use cases, the guest kernel is trusted and the host may +create 100+ VMs per logical CPU, which can result in 100ms+ latencies when +a burst of VMs is created. + +Reported-by: Li RongQing +Closes: https://lore.kernel.org/all/1679555884-32544-1-git-send-email-lirongqing@baidu.com +Cc: Yong He +Cc: Robert Hoo +Cc: Kai Huang +Reviewed-by: Robert Hoo +Acked-by: Kai Huang +Tested-by: Luiz Capitulino +Reviewed-by: Li RongQing +Link: https://lore.kernel.org/r/20230602005859.784190-1-seanjc@google.com +Signed-off-by: Sean Christopherson +Signed-off-by: Luiz Capitulino +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kvm/mmu/mmu.c | 41 ++++++++++++++++++++++++++++++++++++----- + 1 file changed, 36 insertions(+), 5 deletions(-) + +--- a/arch/x86/kvm/mmu/mmu.c ++++ b/arch/x86/kvm/mmu/mmu.c +@@ -58,6 +58,8 @@ + + extern bool itlb_multihit_kvm_mitigation; + ++static bool nx_hugepage_mitigation_hard_disabled; ++ + int __read_mostly nx_huge_pages = -1; + static uint __read_mostly nx_huge_pages_recovery_period_ms; + #ifdef CONFIG_PREEMPT_RT +@@ -67,12 +69,13 @@ static uint __read_mostly nx_huge_pages_ + static uint __read_mostly nx_huge_pages_recovery_ratio = 60; + #endif + ++static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp); + static int set_nx_huge_pages(const char *val, const struct kernel_param *kp); + static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp); + + static const struct kernel_param_ops nx_huge_pages_ops = { + .set = set_nx_huge_pages, +- .get = param_get_bool, ++ .get = get_nx_huge_pages, + }; + + static const struct kernel_param_ops nx_huge_pages_recovery_param_ops = { +@@ -6844,6 +6847,14 @@ static void mmu_destroy_caches(void) + kmem_cache_destroy(mmu_page_header_cache); + } + ++static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp) ++{ ++ if (nx_hugepage_mitigation_hard_disabled) ++ return sprintf(buffer, "never\n"); ++ ++ return param_get_bool(buffer, kp); ++} ++ + static bool get_nx_auto_mode(void) + { + /* Return true when CPU has the bug, and mitigations are ON */ +@@ -6860,15 +6871,29 @@ static int set_nx_huge_pages(const char + bool old_val = nx_huge_pages; + bool new_val; + ++ if (nx_hugepage_mitigation_hard_disabled) ++ return -EPERM; ++ + /* In "auto" mode deploy workaround only if CPU has the bug. */ +- if (sysfs_streq(val, "off")) ++ if (sysfs_streq(val, "off")) { + new_val = 0; +- else if (sysfs_streq(val, "force")) ++ } else if (sysfs_streq(val, "force")) { + new_val = 1; +- else if (sysfs_streq(val, "auto")) ++ } else if (sysfs_streq(val, "auto")) { + new_val = get_nx_auto_mode(); +- else if (kstrtobool(val, &new_val) < 0) ++ } else if (sysfs_streq(val, "never")) { ++ new_val = 0; ++ ++ mutex_lock(&kvm_lock); ++ if (!list_empty(&vm_list)) { ++ mutex_unlock(&kvm_lock); ++ return -EBUSY; ++ } ++ nx_hugepage_mitigation_hard_disabled = true; ++ mutex_unlock(&kvm_lock); ++ } else if (kstrtobool(val, &new_val) < 0) { + return -EINVAL; ++ } + + __set_nx_huge_pages(new_val); + +@@ -7006,6 +7031,9 @@ static int set_nx_huge_pages_recovery_pa + uint old_period, new_period; + int err; + ++ if (nx_hugepage_mitigation_hard_disabled) ++ return -EPERM; ++ + was_recovery_enabled = calc_nx_huge_pages_recovery_period(&old_period); + + err = param_set_uint(val, kp); +@@ -7164,6 +7192,9 @@ int kvm_mmu_post_init_vm(struct kvm *kvm + { + int err; + ++ if (nx_hugepage_mitigation_hard_disabled) ++ return 0; ++ + err = kvm_vm_create_worker_thread(kvm, kvm_nx_huge_page_recovery_worker, 0, + "kvm-nx-lpage-recovery", + &kvm->arch.nx_huge_page_recovery_thread); diff --git a/queue-6.4/series b/queue-6.4/series index a6850f43ca0..e9ea84630e5 100644 --- a/queue-6.4/series +++ b/queue-6.4/series @@ -86,3 +86,4 @@ platform-mellanox-fix-mlxbf-tmfifo-not-handling-all-.patch sbitmap-fix-batching-wakeup.patch cpufreq-intel_pstate-set-stale-cpu-frequency-to-minimum.patch tpm-enable-hwrng-only-for-pluton-on-amd-cpus.patch +kvm-x86-mmu-add-never-option-to-allow-sticky-disabling-of-nx_huge_pages.patch -- 2.47.3