From: Vlastimil Babka <vbabka@suse.cz>
To: Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org
Cc: linux-coco@lists.linux.dev, linux-mm@kvack.org,
linux-crypto@vger.kernel.org, x86@kernel.org,
linux-kernel@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,
pgonda@google.com, peterz@infradead.org,
srinivas.pandruvada@linux.intel.com, rientjes@google.com,
dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de,
kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com,
marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com,
alpergun@google.com, jarkko@kernel.org, ashish.kalra@amd.com,
nikunj.dadhania@amd.com, pankaj.gupta@amd.com,
liam.merwick@oracle.com, zhi.a.wang@intel.com,
Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [PATCH v10 23/50] KVM: SEV: Make AVIC backing, VMSA and VMCB memory allocation SNP safe
Date: Mon, 11 Dec 2023 14:24:34 +0100 [thread overview]
Message-ID: <20e52d79-7eff-1aad-2f77-24ed7fd56fa7@suse.cz> (raw)
In-Reply-To: <20231016132819.1002933-24-michael.roth@amd.com>
On 10/16/23 15:27, Michael Roth wrote:
> From: Brijesh Singh <brijesh.singh@amd.com>
>
> Implement a workaround for an SNP erratum where the CPU will incorrectly
> signal an RMP violation #PF if a hugepage (2mb or 1gb) collides with the
> RMP entry of a VMCB, VMSA or AVIC backing page.
>
> When SEV-SNP is globally enabled, the CPU marks the VMCB, VMSA, and AVIC
> backing pages as "in-use" via a reserved bit in the corresponding RMP
> entry after a successful VMRUN. This is done for _all_ VMs, not just
> SNP-Active VMs.
>
> If the hypervisor accesses an in-use page through a writable
> translation, the CPU will throw an RMP violation #PF. On early SNP
> hardware, if an in-use page is 2mb aligned and software accesses any
> part of the associated 2mb region with a hupage, the CPU will
> incorrectly treat the entire 2mb region as in-use and signal a spurious
> RMP violation #PF.
>
> The recommended is to not use the hugepage for the VMCB, VMSA or
> AVIC backing page for similar reasons. Add a generic allocator that will
> ensure that the page returns is not hugepage (2mb or 1gb) and is safe to
This is a bit confusing wording as we are not avoiding "using a
hugepage" but AFAIU, avoiding using a (4k) page that has a hugepage
aligned physical address, right?
> be used when SEV-SNP is enabled. Also implement similar handling for the
> VMCB/VMSA pages of nested guests.
>
> Co-developed-by: Marc Orr <marcorr@google.com>
> Signed-off-by: Marc Orr <marcorr@google.com>
> Reported-by: Alper Gun <alpergun@google.com> # for nested VMSA case
> Co-developed-by: Ashish Kalra <ashish.kalra@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> [mdr: squash in nested guest handling from Ashish]
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> ---
<snip>
> +
> +struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu)
> +{
> + unsigned long pfn;
> + struct page *p;
> +
> + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
> + return alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> +
> + /*
> + * Allocate an SNP safe page to workaround the SNP erratum where
> + * the CPU will incorrectly signal an RMP violation #PF if a
> + * hugepage (2mb or 1gb) collides with the RMP entry of VMCB, VMSA
> + * or AVIC backing page. The recommeded workaround is to not use the
> + * hugepage.
Same here "not use the hugepage"
> + *
> + * Allocate one extra page, use a page which is not 2mb aligned
> + * and free the other.
This makes more sense.
> + */
> + p = alloc_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1);
> + if (!p)
> + return NULL;
> +
> + split_page(p, 1);
Yeah I think that's a sensible use of split_page(), as we don't have
support for forcefully non-aligned allocations or specific "page
coloring" in the page allocator.
So even with my wording concerns:
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> +
> + pfn = page_to_pfn(p);
> + if (IS_ALIGNED(pfn, PTRS_PER_PMD))
> + __free_page(p++);
> + else
> + __free_page(p + 1);
> +
> + return p;
> +}
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 1e7fb1ea45f7..8e4ef0cd968a 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -706,7 +706,7 @@ static int svm_cpu_init(int cpu)
> int ret = -ENOMEM;
>
> memset(sd, 0, sizeof(struct svm_cpu_data));
> - sd->save_area = alloc_page(GFP_KERNEL | __GFP_ZERO);
> + sd->save_area = snp_safe_alloc_page(NULL);
> if (!sd->save_area)
> return ret;
>
> @@ -1425,7 +1425,7 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
> svm = to_svm(vcpu);
>
> err = -ENOMEM;
> - vmcb01_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> + vmcb01_page = snp_safe_alloc_page(vcpu);
> if (!vmcb01_page)
> goto out;
>
> @@ -1434,7 +1434,7 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
> * SEV-ES guests require a separate VMSA page used to contain
> * the encrypted register state of the guest.
> */
> - vmsa_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> + vmsa_page = snp_safe_alloc_page(vcpu);
> if (!vmsa_page)
> goto error_free_vmcb_page;
>
> @@ -4876,6 +4876,16 @@ static int svm_vm_init(struct kvm *kvm)
> return 0;
> }
>
> +static void *svm_alloc_apic_backing_page(struct kvm_vcpu *vcpu)
> +{
> + struct page *page = snp_safe_alloc_page(vcpu);
> +
> + if (!page)
> + return NULL;
> +
> + return page_address(page);
> +}
> +
> static struct kvm_x86_ops svm_x86_ops __initdata = {
> .name = KBUILD_MODNAME,
>
> @@ -5007,6 +5017,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
>
> .vcpu_deliver_sipi_vector = svm_vcpu_deliver_sipi_vector,
> .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons,
> + .alloc_apic_backing_page = svm_alloc_apic_backing_page,
> };
>
> /*
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index c13070d00910..b7b8bf73cbb9 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -694,6 +694,7 @@ void sev_es_vcpu_reset(struct vcpu_svm *svm);
> void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
> 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);
>
> /* vmenter.S */
>
next prev parent reply other threads:[~2023-12-11 13:24 UTC|newest]
Thread overview: 158+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-16 13:27 [PATCH v10 00/50] Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support Michael Roth
2023-10-16 13:27 ` [PATCH v10 01/50] KVM: SVM: INTERCEPT_RDTSCP is never intercepted anyway Michael Roth
2023-10-16 15:12 ` Greg KH
2023-10-16 15:14 ` Paolo Bonzini
2023-10-16 15:21 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 02/50] KVM: SVM: Fix TSC_AUX virtualization setup Michael Roth
2023-10-16 13:27 ` [PATCH v10 03/50] KVM: SEV: Do not intercept accesses to MSR_IA32_XSS for SEV-ES guests Michael Roth
2023-12-13 12:50 ` Paolo Bonzini
2023-12-13 17:30 ` Sean Christopherson
2023-12-13 17:40 ` Paolo Bonzini
2023-10-16 13:27 ` [PATCH v10 04/50] x86/cpufeatures: Add SEV-SNP CPU feature Michael Roth
2023-12-13 12:51 ` Paolo Bonzini
2023-12-13 13:13 ` Borislav Petkov
2023-12-13 13:31 ` Paolo Bonzini
2023-12-13 13:36 ` Borislav Petkov
2023-12-13 13:40 ` Paolo Bonzini
2023-12-13 13:49 ` Borislav Petkov
2023-12-13 14:18 ` Paolo Bonzini
2023-12-13 15:41 ` Borislav Petkov
2023-12-13 17:35 ` Paolo Bonzini
2023-12-13 18:53 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 05/50] x86/speculation: Do not enable Automatic IBRS if SEV SNP is enabled Michael Roth
2023-10-25 17:33 ` Borislav Petkov
2023-10-27 21:50 ` Dave Hansen
2023-12-13 12:52 ` Paolo Bonzini
2023-10-16 13:27 ` [PATCH v10 06/50] x86/sev: Add the host SEV-SNP initialization support Michael Roth
2023-10-25 18:19 ` Tom Lendacky
2023-11-07 16:31 ` Borislav Petkov
2023-11-07 18:32 ` Tom Lendacky
2023-11-07 19:13 ` Borislav Petkov
2023-11-08 8:21 ` Jeremi Piotrowski
2023-11-08 15:19 ` Tom Lendacky
2023-11-07 19:00 ` Kalra, Ashish
2023-11-07 19:19 ` Borislav Petkov
2023-11-07 20:27 ` Borislav Petkov
2023-11-07 21:21 ` Kalra, Ashish
2023-11-07 21:27 ` Borislav Petkov
2023-11-07 22:08 ` Borislav Petkov
2023-11-07 22:33 ` Kalra, Ashish
2023-11-08 6:14 ` Borislav Petkov
2023-11-08 9:11 ` Jeremi Piotrowski
2023-11-08 19:53 ` Kalra, Ashish
2023-12-08 17:09 ` Jeremi Piotrowski
2023-12-08 23:21 ` Kalra, Ashish
2023-12-20 7:07 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 07/50] x86/sev: Add RMP entry lookup helpers Michael Roth
2023-11-14 14:24 ` Borislav Petkov
2023-12-19 3:31 ` Michael Roth
2024-01-09 22:07 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 08/50] x86/fault: Add helper for dumping RMP entries Michael Roth
2023-11-15 16:08 ` Borislav Petkov
2023-12-19 6:08 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 09/50] x86/traps: Define RMP violation #PF error code Michael Roth
2023-10-16 14:14 ` Dave Hansen
2023-10-16 14:55 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 10/50] x86/fault: Report RMP page faults for kernel addresses Michael Roth
2023-11-21 15:23 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 11/50] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction Michael Roth
2023-11-21 16:21 ` Borislav Petkov
2023-12-19 16:20 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 12/50] x86/sev: Invalidate pages from the direct map when adding them to the RMP table Michael Roth
2023-11-24 14:20 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 13/50] crypto: ccp: Define the SEV-SNP commands Michael Roth
2023-11-24 14:36 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 14/50] crypto: ccp: Add support to initialize the AMD-SP for SEV-SNP Michael Roth
2023-11-27 9:59 ` Borislav Petkov
2023-11-30 2:13 ` Kalra, Ashish
2023-12-06 17:08 ` Borislav Petkov
2023-12-06 20:35 ` Kalra, Ashish
2023-12-09 16:20 ` Borislav Petkov
2023-12-11 21:11 ` Kalra, Ashish
2023-12-12 6:52 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 15/50] crypto: ccp: Provide API to issue SEV and SNP commands Michael Roth
2023-12-06 20:21 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 16/50] x86/sev: Introduce snp leaked pages list Michael Roth
2023-12-06 20:42 ` Borislav Petkov
2023-12-08 20:54 ` Kalra, Ashish
2023-12-07 16:20 ` Vlastimil Babka
2023-12-08 22:10 ` Kalra, Ashish
2023-12-11 13:08 ` Vlastimil Babka
2023-12-12 23:26 ` Kalra, Ashish
2023-10-16 13:27 ` [PATCH v10 17/50] crypto: ccp: Handle the legacy TMR allocation when SNP is enabled Michael Roth
2023-12-08 13:05 ` Borislav Petkov
2023-12-19 23:46 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 18/50] crypto: ccp: Handle the legacy SEV command " Michael Roth
2023-12-09 15:36 ` Borislav Petkov
2023-12-29 21:38 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 19/50] crypto: ccp: Add the SNP_PLATFORM_STATUS command Michael Roth
2023-12-12 16:45 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 20/50] KVM: SEV: Select CONFIG_KVM_SW_PROTECTED_VM when CONFIG_KVM_AMD_SEV=y Michael Roth
2023-12-13 12:54 ` Paolo Bonzini
2023-12-29 21:41 ` Michael Roth
2023-12-18 10:13 ` Borislav Petkov
2023-12-29 21:40 ` Michael Roth
2023-10-16 13:27 ` [PATCH v10 21/50] KVM: SEV: Add support to handle AP reset MSR protocol Michael Roth
2023-12-12 17:02 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 22/50] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests Michael Roth
2023-12-18 10:23 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 23/50] KVM: SEV: Make AVIC backing, VMSA and VMCB memory allocation SNP safe Michael Roth
2023-12-11 13:24 ` Vlastimil Babka [this message]
2023-12-12 0:00 ` Kalra, Ashish
2023-12-13 13:31 ` Paolo Bonzini
2023-12-13 18:45 ` Paolo Bonzini
2023-12-18 14:57 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 24/50] KVM: SEV: Add initial SEV-SNP support Michael Roth
2023-12-18 17:43 ` Borislav Petkov
2023-10-16 13:27 ` [PATCH v10 25/50] KVM: SEV: Add KVM_SNP_INIT command Michael Roth
2023-10-16 13:27 ` [PATCH v10 26/50] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_START command Michael Roth
2023-10-16 13:27 ` [PATCH v10 27/50] KVM: Add HVA range operator Michael Roth
2023-10-16 13:27 ` [PATCH v10 28/50] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_UPDATE command Michael Roth
2023-10-16 13:27 ` [PATCH v10 29/50] KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command Michael Roth
2023-10-16 13:27 ` [PATCH v10 30/50] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT Michael Roth
2023-10-16 13:28 ` [PATCH v10 31/50] KVM: SEV: Add KVM_EXIT_VMGEXIT Michael Roth
2023-10-16 13:28 ` [PATCH v10 32/50] KVM: SEV: Add support to handle MSR based Page State Change VMGEXIT Michael Roth
2023-10-16 13:28 ` [PATCH v10 33/50] KVM: SEV: Add support to handle " Michael Roth
2023-10-16 13:28 ` [PATCH v10 34/50] KVM: x86: Export the kvm_zap_gfn_range() for the SNP use Michael Roth
2023-10-16 13:28 ` [PATCH v10 35/50] KVM: SEV: Add support to handle RMP nested page faults Michael Roth
2023-10-16 13:28 ` [PATCH v10 36/50] KVM: SEV: Use a VMSA physical address variable for populating VMCB Michael Roth
2023-10-16 13:28 ` [PATCH v10 37/50] KVM: SEV: Support SEV-SNP AP Creation NAE event Michael Roth
2023-10-16 13:28 ` [PATCH v10 38/50] KVM: SEV: Add support for GHCB-based termination requests Michael Roth
2023-10-19 12:20 ` Liam Merwick
2023-10-16 13:28 ` [PATCH v10 39/50] KVM: SEV: Implement gmem hook for initializing private pages Michael Roth
2023-10-16 13:28 ` [PATCH v10 40/50] KVM: SEV: Implement gmem hook for invalidating " Michael Roth
2023-10-16 13:28 ` [PATCH v10 41/50] KVM: x86: Add gmem hook for determining max NPT mapping level Michael Roth
2023-10-16 13:28 ` [PATCH v10 42/50] KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP Michael Roth
2023-10-16 13:28 ` [PATCH v10 43/50] KVM: SVM: Add module parameter to enable the SEV-SNP Michael Roth
2023-10-16 13:28 ` [PATCH v10 44/50] iommu/amd: Add IOMMU_SNP_SHUTDOWN support Michael Roth
2023-10-16 13:28 ` [PATCH v10 45/50] iommu/amd: Report all cases inhibiting SNP enablement Michael Roth
2023-10-16 13:28 ` [PATCH v10 46/50] crypto: ccp: Add the SNP_{SET,GET}_EXT_CONFIG command Michael Roth
2023-10-16 23:11 ` Dionna Amalie Glaze
2023-10-16 13:28 ` [PATCH v10 47/50] x86/sev: Add KVM commands for per-instance certs Michael Roth
2023-10-16 13:28 ` [PATCH v10 48/50] KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event Michael Roth
2023-10-16 23:18 ` Dionna Amalie Glaze
2023-10-17 16:27 ` Sean Christopherson
2023-10-18 2:28 ` Alexey Kardashevskiy
2023-10-18 13:48 ` Sean Christopherson
2023-10-18 20:27 ` Kalra, Ashish
2023-10-18 20:38 ` Sean Christopherson
2023-10-18 21:27 ` Kalra, Ashish
2023-10-18 21:43 ` Sean Christopherson
2023-10-19 2:48 ` Alexey Kardashevskiy
2023-10-19 14:57 ` Sean Christopherson
2023-10-19 23:55 ` Alexey Kardashevskiy
2023-10-20 0:13 ` Sean Christopherson
2023-10-20 0:43 ` Alexey Kardashevskiy
2023-10-20 15:13 ` Sean Christopherson
2023-10-20 18:37 ` Tom Lendacky
2023-11-10 22:07 ` Michael Roth
2023-11-10 22:47 ` Sean Christopherson
2023-11-16 5:31 ` Dionna Amalie Glaze
2023-12-05 0:30 ` Dan Williams
2023-12-05 0:48 ` Dionna Amalie Glaze
2023-12-05 20:06 ` Dan Williams
2023-12-05 22:04 ` Dionna Amalie Glaze
2023-12-05 23:11 ` Dan Williams
2023-12-06 0:43 ` Dionna Amalie Glaze
2023-10-16 13:28 ` [PATCH v10 49/50] crypto: ccp: Add debug support for decrypting pages Michael Roth
2023-10-16 13:28 ` [PATCH v10 50/50] crypto: ccp: Add panic notifier for SEV/SNP firmware shutdown on kdump Michael Roth
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