From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f53.google.com (mail-lf1-f53.google.com [209.85.167.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5EA458BFD for ; Thu, 17 Nov 2022 20:19:11 +0000 (UTC) Received: by mail-lf1-f53.google.com with SMTP id s8so4691571lfc.8 for ; Thu, 17 Nov 2022 12:19:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=gkna0fGiQVgsVnWMqH15LxACPZ+dyslkPZRcyoaRi8M=; b=OzToyQ5Dh8TZrMYBHIsP3Q/47IMkrNFnTJJXVrqS+RlMasplhLwlVH83ktgHJrFOAq qAbOJTVvCppju6/uRrI1aJnJCHRE/Lq2SOaXB8xIeRl4GHv2yWb4+nV9Spk9hD31S9yk Oao0kzxD5wiVF1In1F70HeHQozb4wyHDkj1mqicZL9a/5RJtktYIK2Ijwi2h/XxNpzLx dd3aLEc8lEKOzTD37V8gAz2KqKjC4aXrh4SJg7g3UaZ6NHP5o7zBoliiF9uOsG7Fmng4 Cd4o94Za5ocA8zz8UzCwHqYvXtp95mAnDQP15wdk/IbiMG/uUrnFwpq8RzRhdiUOFWXT oUYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=gkna0fGiQVgsVnWMqH15LxACPZ+dyslkPZRcyoaRi8M=; b=fV/vktbegHynafazLeD3vHhd1l3yH38DanbYVuDVgAeAsrabENHdjltO5nK1mrnAz/ UPubEKHyCqxgnz4sEBYK6w5D6PAjlg4o6ZEQKTcSHoh4H8UcEiLiqIRFxw6yldxBPK9i 3Pu/VFWpOQVtGtF9nH7nhx6dyAj8+RS1L2niBsc+D2YR4Rm+bHTW4HbHMBXiHiDzemZe HGYlp4LMPApYOeA0puYeYPuF3AA4g1lgDBvNiusA5ONXCRGjv2j9ciUlY4gsGUgyjsrG X6HGSrHbNFZh6s8TR9bxV3pfXjqsipjUetYL07EMEWm7Ksb4cvkvq8/v1Z4KsoOaAN1+ IncA== X-Gm-Message-State: ANoB5plppPi+M3u9pH08xjGgq3i79GocXg/idWI0AdZaE4SY+R/Wm8S9 IGh/mLSCedcqfHWhQtfEjePtgH5+agE+Iq0w3oQLRg== X-Google-Smtp-Source: AA0mqf71072s2CdC2GkbpswjF86mN2Xp1QB6r5agNd51lGwb4YhkKKwMKcc7+oVhqUKdODhNaMXBEKq1K0ihbeC+l84= X-Received: by 2002:a05:6512:281b:b0:4b3:e086:87d8 with SMTP id cf27-20020a056512281b00b004b3e08687d8mr1373158lfb.259.1668716348908; Thu, 17 Nov 2022 12:19:08 -0800 (PST) Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <34246866043db7bab34a92fe22f359667ab155a0.1655761627.git.ashish.kalra@amd.com> In-Reply-To: From: Peter Gonda Date: Thu, 17 Nov 2022 13:18:57 -0700 Message-ID: Subject: Re: [PATCH Part2 v6 39/49] KVM: SVM: Introduce ops for the post gfn map and unmap To: Alper Gun Cc: Ashish Kalra , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, michael.roth@amd.com, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, dgilbert@redhat.com, jarkko@kernel.org Content-Type: text/plain; charset="UTF-8" On Wed, Aug 17, 2022 at 9:47 PM Alper Gun wrote: > > On Mon, Jun 20, 2022 at 4:12 PM Ashish Kalra wrote: > > > > From: Brijesh Singh > > > > When SEV-SNP is enabled in the guest VM, the guest memory pages can > > either be a private or shared. A write from the hypervisor goes through > > the RMP checks. If hardware sees that hypervisor is attempting to write > > to a guest private page, then it triggers an RMP violation #PF. > > > > To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn > > functions to verify if its safe to map GHCB pages. Uses a spinlock to > > protect against the page state change for existing mapped pages. > > > > Need to add generic post_{map,unmap}_gfn() ops that can be used to verify > > that its safe to map a given guest page in the hypervisor. > > > > This patch will need to be revisited later after consensus is reached on > > how to manage guest private memory as probably UPM private memslots will > > be able to handle this page state change more gracefully. > > > > Signed-off-by: Brijesh Singh > > Signed-off by: Ashish Kalra > > --- > > arch/x86/include/asm/kvm-x86-ops.h | 1 + > > arch/x86/include/asm/kvm_host.h | 3 ++ > > arch/x86/kvm/svm/sev.c | 48 ++++++++++++++++++++++++++++-- > > arch/x86/kvm/svm/svm.c | 3 ++ > > arch/x86/kvm/svm/svm.h | 11 +++++++ > > 5 files changed, 64 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h > > index e0068e702692..2dd2bc0cf4c3 100644 > > --- a/arch/x86/include/asm/kvm-x86-ops.h > > +++ b/arch/x86/include/asm/kvm-x86-ops.h > > @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) > > KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); > > KVM_X86_OP(alloc_apic_backing_page) > > KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) > > +KVM_X86_OP(update_protected_guest_state) > > > > #undef KVM_X86_OP > > #undef KVM_X86_OP_OPTIONAL > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 49b217dc8d7e..8abc0e724f5c 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { > > unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); > > > > void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); > > + > > void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); > > + > > + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); > > }; > > > > struct kvm_x86_nested_ops { > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > > index cb2d1bbb862b..4ed90331bca0 100644 > > --- a/arch/x86/kvm/svm/sev.c > > +++ b/arch/x86/kvm/svm/sev.c > > @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > > if (ret) > > goto e_free; > > > > + spin_lock_init(&sev->psc_lock); > > ret = sev_snp_init(&argp->error); > > } else { > > ret = sev_platform_init(&argp->error); > > @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > > { > > struct vmcb_control_area *control = &svm->vmcb->control; > > u64 gfn = gpa_to_gfn(control->ghcb_gpa); > > + struct kvm_vcpu *vcpu = &svm->vcpu; > > > > - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { > > + if (kvm_vcpu_map(vcpu, gfn, map)) { > > /* Unable to map GHCB from guest */ > > pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); > > return -EFAULT; > > } > > > > + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { > > + kvm_vcpu_unmap(vcpu, map, false); > > + return -EBUSY; > > + } > > + > > return 0; > > } > > > > static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > > { > > - kvm_vcpu_unmap(&svm->vcpu, map, true); > > + struct kvm_vcpu *vcpu = &svm->vcpu; > > + > > + kvm_vcpu_unmap(vcpu, map, true); > > + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); > > } > > > > static void dump_ghcb(struct vcpu_svm *svm) > > @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > > return PSC_UNDEF_ERR; > > } > > > > + spin_lock(&sev->psc_lock); > > + > > write_lock(&kvm->mmu_lock); > > > > rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); > > @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > > > > write_unlock(&kvm->mmu_lock); > > > > + spin_unlock(&sev->psc_lock); > > There is a corner case where the psc_lock is not released. If > kvm_mmu_get_tdp_walk fails, the lock will be kept and will cause soft > lockup. > > > + > > if (rc) { > > pr_err_ratelimited("Error op %d gpa %llx pfn %llx level %d rc %d\n", > > op, gpa, pfn, level, rc); > > @@ -3965,3 +3979,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) > > /* Adjust the level to keep the NPT and RMP in sync */ > > *level = min_t(size_t, *level, rmp_level); > > } > > + > > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + int level; > > + > > + if (!sev_snp_guest(kvm)) > > + return 0; > > + > > + spin_lock(&sev->psc_lock); > > + > > + /* If pfn is not added as private then fail */ > > + if (snp_lookup_rmpentry(pfn, &level) == 1) { > > + spin_unlock(&sev->psc_lock); > > + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); > > + return -EBUSY; > > + } > > + > > + return 0; > > +} > > + > > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + > > + if (!sev_snp_guest(kvm)) > > + return; > > + > > + spin_unlock(&sev->psc_lock); > > +} > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > index b24e0171cbf2..1c8e035ba011 100644 > > --- a/arch/x86/kvm/svm/svm.c > > +++ b/arch/x86/kvm/svm/svm.c > > @@ -4734,7 +4734,10 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { > > .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, > > > > .alloc_apic_backing_page = svm_alloc_apic_backing_page, > > + > > .rmp_page_level_adjust = sev_rmp_page_level_adjust, > > + > > + .update_protected_guest_state = sev_snp_update_protected_guest_state, > > }; I don't see this function sev_snp_update_protected_guest_state() being defined anywhere in this series. Then this line is removed in 'KVM: SVM: Support SEV-SNP AP Creation NAE event'. Should this line just be removed from this patch in the first place? > > > > /* > > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > > index 54ff56cb6125..3fd95193ed8d 100644 > > --- a/arch/x86/kvm/svm/svm.h > > +++ b/arch/x86/kvm/svm/svm.h > > @@ -79,19 +79,25 @@ struct kvm_sev_info { > > bool active; /* SEV enabled guest */ > > bool es_active; /* SEV-ES enabled guest */ > > bool snp_active; /* SEV-SNP enabled guest */ > > + > > unsigned int asid; /* ASID used for this guest */ > > unsigned int handle; /* SEV firmware handle */ > > int fd; /* SEV device fd */ > > + > > unsigned long pages_locked; /* Number of pages locked */ > > struct list_head regions_list; /* List of registered regions */ > > + > > u64 ap_jump_table; /* SEV-ES AP Jump Table address */ > > + > > struct kvm *enc_context_owner; /* Owner of copied encryption context */ > > struct list_head mirror_vms; /* List of VMs mirroring */ > > struct list_head mirror_entry; /* Use as a list entry of mirrors */ > > struct misc_cg *misc_cg; /* For misc cgroup accounting */ > > atomic_t migration_in_progress; > > + > > u64 snp_init_flags; > > void *snp_context; /* SNP guest context page */ > > + spinlock_t psc_lock; > > }; > > > > struct kvm_svm { > > @@ -702,6 +708,11 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); > > void sev_es_unmap_ghcb(struct vcpu_svm *svm); > > struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); > > void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); > > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > > +void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); > > +void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); > > +int sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu); Ditto should this be removed? > > > > /* vmenter.S */ > > > > -- > > 2.25.1 > >