| Message ID | 20211019121848.245347-1-liyu.yukiteru@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: Warn on nx_huge_pages when initializing kvm | expand |
On 19/10/21 14:18, Li Yu wrote: > Add warning when `nx_huge_pages` is enabled by kvm mmu for hint that > huge pages may be splited by kernel. > > Signed-off-by: Li Yu <liyu.yukiteru@bytedance.com> > --- > arch/x86/kvm/mmu/mmu.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 1a64ba5b9437..b75dbaf29f2d 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -6091,12 +6091,17 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) > return 0; > } > > +#define ITLB_MULTIHIT_MSG "iTLB multi-hit CPU bug present and cpu mitigations enabled, huge pages may be splited by kernel for security. See CVE-2018-12207 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/multihit.html for details.\n" Shouldn't it warn if mitigations are disabled but the bug is present? Paolo > int kvm_mmu_module_init(void) > { > int ret = -ENOMEM; > > - if (nx_huge_pages == -1) > + if (nx_huge_pages == -1) { > __set_nx_huge_pages(get_nx_auto_mode()); > + if (is_nx_huge_page_enabled()) > + pr_warn_once(ITLB_MULTIHIT_MSG); > + } > > /* > * MMU roles use union aliasing which is, generally speaking, an >
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 1a64ba5b9437..b75dbaf29f2d 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6091,12 +6091,17 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) return 0; } +#define ITLB_MULTIHIT_MSG "iTLB multi-hit CPU bug present and cpu mitigations enabled, huge pages may be splited by kernel for security. See CVE-2018-12207 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/multihit.html for details.\n" + int kvm_mmu_module_init(void) { int ret = -ENOMEM; - if (nx_huge_pages == -1) + if (nx_huge_pages == -1) { __set_nx_huge_pages(get_nx_auto_mode()); + if (is_nx_huge_page_enabled()) + pr_warn_once(ITLB_MULTIHIT_MSG); + } /* * MMU roles use union aliasing which is, generally speaking, an
Add warning when `nx_huge_pages` is enabled by kvm mmu for hint that huge pages may be splited by kernel. Signed-off-by: Li Yu <liyu.yukiteru@bytedance.com> --- arch/x86/kvm/mmu/mmu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)