From f098de42a152e17665ddf370f67c932d0a00838a Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 16 May 2019 16:43:26 +0800 Subject: [PATCH] x86/kvm/vmx: Add MDS protection when L1D Flush is not active commit 650b68a0622f933444a6d66936abb3103029413b upstream CPUs which are affected by L1TF and MDS mitigate MDS with the L1D Flush on VMENTER when updated microcode is installed. If a CPU is not affected by L1TF or if the L1D Flush is not in use, then MDS mitigation needs to be invoked explicitly. For these cases, follow the host mitigation state and invoke the MDS mitigation before VMENTER. Signed-off-by: Thomas Gleixner Reviewed-by: Greg Kroah-Hartman Reviewed-by: Frederic Weisbecker Reviewed-by: Borislav Petkov Reviewed-by: Jon Masters Tested-by: Jon Masters Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- arch/x86/kernel/cpu/bugs.c | 1 + arch/x86/kvm/vmx.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 2a69046cc38c..c01468ccefc1 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -63,6 +63,7 @@ DEFINE_STATIC_KEY_FALSE(switch_mm_always_ibpb); /* Control MDS CPU buffer clear before returning to user space */ DEFINE_STATIC_KEY_FALSE(mds_user_clear); +EXPORT_SYMBOL_GPL(mds_user_clear); void __init check_bugs(void) { diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 215339c7d161..e9bf477209dc 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10765,8 +10765,11 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu) evmcs_rsp = static_branch_unlikely(&enable_evmcs) ? (unsigned long)¤t_evmcs->host_rsp : 0; + /* L1D Flush includes CPU buffer clear to mitigate MDS */ if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); + else if (static_branch_unlikely(&mds_user_clear)) + mds_clear_cpu_buffers(); asm( /* Store host registers */ -- GitLab