From bb18a677746543e7f5eeb478129c92cedb0f9658 Mon Sep 17 00:00:00 2001 From: Peter Gonda Date: Wed, 15 Sep 2021 10:17:55 -0700 Subject: [PATCH] KVM: SEV: Acquire vcpu mutex when updating VMSA The update-VMSA ioctl touches data stored in struct kvm_vcpu, and therefore should not be performed concurrently with any VCPU ioctl that might cause KVM or the processor to use the same data. Adds vcpu mutex guard to the VMSA updating code. Refactors out __sev_launch_update_vmsa() function to deal with per vCPU parts of sev_launch_update_vmsa(). Fixes: ad73109ae7ec ("KVM: SVM: Provide support to launch and run an SEV-ES guest") Signed-off-by: Peter Gonda Cc: Marc Orr Cc: Paolo Bonzini Cc: Sean Christopherson Cc: Brijesh Singh Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Message-Id: <20210915171755.3773766-1-pgonda@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/sev.c | 51 ++++++++++++++++++++++++------------------ 1 file changed, 29 insertions(+), 22 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 75e0b21ad07c..61c4bf4b3a0a 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -595,43 +595,50 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm) return 0; } +static int __sev_launch_update_vmsa(struct kvm *kvm, struct kvm_vcpu *vcpu, + int *error) +{ + struct sev_data_launch_update_vmsa vmsa; + struct vcpu_svm *svm = to_svm(vcpu); + int ret; + + /* Perform some pre-encryption checks against the VMSA */ + ret = sev_es_sync_vmsa(svm); + if (ret) + return ret; + + /* + * The LAUNCH_UPDATE_VMSA command will perform in-place encryption of + * the VMSA memory content (i.e it will write the same memory region + * with the guest's key), so invalidate it first. + */ + clflush_cache_range(svm->vmsa, PAGE_SIZE); + + vmsa.reserved = 0; + vmsa.handle = to_kvm_svm(kvm)->sev_info.handle; + vmsa.address = __sme_pa(svm->vmsa); + vmsa.len = PAGE_SIZE; + return sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE_VMSA, &vmsa, error); +} + static int sev_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) { - struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; - struct sev_data_launch_update_vmsa vmsa; struct kvm_vcpu *vcpu; int i, ret; if (!sev_es_guest(kvm)) return -ENOTTY; - vmsa.reserved = 0; - kvm_for_each_vcpu(i, vcpu, kvm) { - struct vcpu_svm *svm = to_svm(vcpu); - - /* Perform some pre-encryption checks against the VMSA */ - ret = sev_es_sync_vmsa(svm); + ret = mutex_lock_killable(&vcpu->mutex); if (ret) return ret; - /* - * The LAUNCH_UPDATE_VMSA command will perform in-place - * encryption of the VMSA memory content (i.e it will write - * the same memory region with the guest's key), so invalidate - * it first. - */ - clflush_cache_range(svm->vmsa, PAGE_SIZE); + ret = __sev_launch_update_vmsa(kvm, vcpu, &argp->error); - vmsa.handle = sev->handle; - vmsa.address = __sme_pa(svm->vmsa); - vmsa.len = PAGE_SIZE; - ret = sev_issue_cmd(kvm, SEV_CMD_LAUNCH_UPDATE_VMSA, &vmsa, - &argp->error); + mutex_unlock(&vcpu->mutex); if (ret) return ret; - - svm->vcpu.arch.guest_state_protected = true; } return 0;