From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DDF7D29AD for ; Tue, 12 Jul 2022 16:44:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1BB16C3411C; Tue, 12 Jul 2022 16:44:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657644297; bh=A9wVtPl9xSGq+0nbgHMGXdDdz52JColikvRDP/5TqlE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XXX4SivkRl90RB6ZxgtEMS08z8/6YjIM5XA75D7z1E9vNByWl7rCmFp5eVcgVf4Nx UKBnlg6BV1w9O29ltCPFR/NAby6C/mX8oHYedjNesUTLy6VPIHNXon8JXxKtK5f4K6 fMF9e6tqTy+L0n8cEbTXok+izu3bdKO1Om51m2mqyyW9SmenkxbH9hAqZlVKUp+apk 0WrCii8LqESl3x32sCaiT5f46qfz9/do8S2tCCNH8u8rXj/hsvwZeQXEXkHgoFEFJD oJj3JRasbFoXgwJM+qQwvqtkD9a9AsjwNSdKwLrkjz1eTSBQZ/PqUs3GHDgpGo+j9T rah9KjVLyKZaQ== Date: Tue, 12 Jul 2022 19:44:54 +0300 From: Jarkko Sakkinen To: Ashish Kalra Cc: 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, pgonda@google.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, alpergun@google.com, dgilbert@redhat.com Subject: Re: [PATCH Part2 v6 29/49] KVM: X86: Keep the NPT and RMP page level in sync Message-ID: References: Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: s/X86/x86/ On Mon, Jun 20, 2022 at 11:08:57PM +0000, Ashish Kalra wrote: > From: Brijesh Singh > > When running an SEV-SNP VM, the sPA used to index the RMP entry is > obtained through the NPT translation (gva->gpa->spa). The NPT page > level is checked against the page level programmed in the RMP entry. > If the page level does not match, then it will cause a nested page > fault with the RMP bit set to indicate the RMP violation. > > Signed-off-by: Brijesh Singh > --- > arch/x86/include/asm/kvm-x86-ops.h | 1 + > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/mmu/mmu.c | 5 ++++ > arch/x86/kvm/svm/sev.c | 46 ++++++++++++++++++++++++++++++ > arch/x86/kvm/svm/svm.c | 1 + > arch/x86/kvm/svm/svm.h | 1 + > 6 files changed, 55 insertions(+) > > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h > index a66292dae698..e0068e702692 100644 > --- a/arch/x86/include/asm/kvm-x86-ops.h > +++ b/arch/x86/include/asm/kvm-x86-ops.h > @@ -129,6 +129,7 @@ KVM_X86_OP(complete_emulated_msr) > 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) > > #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 0205e2944067..2748c69609e3 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1514,6 +1514,7 @@ 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); > }; > > struct kvm_x86_nested_ops { > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index c623019929a7..997318ecebd1 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -43,6 +43,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -2824,6 +2825,10 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, > if (unlikely(!pte)) > return PG_LEVEL_4K; > > + /* Adjust the page level based on the SEV-SNP RMP page level. */ > + if (kvm_x86_ops.rmp_page_level_adjust) > + static_call(kvm_x86_rmp_page_level_adjust)(kvm, pfn, &level); > + > return level; > } > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index a5b90469683f..91d3d24e60d2 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -3597,3 +3597,49 @@ struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu) > > return pfn_to_page(pfn); > } > + > +static bool is_pfn_range_shared(kvm_pfn_t start, kvm_pfn_t end) > +{ > + int level; > + > + while (end > start) { > + if (snp_lookup_rmpentry(start, &level) != 0) > + return false; > + start++; > + } > + > + return true; > +} > + > +void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) Would not do harm to document this, given that it is not a static fuction. > +{ > + int rmp_level, assigned; > + > + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) > + return; > + > + assigned = snp_lookup_rmpentry(pfn, &rmp_level); > + if (unlikely(assigned < 0)) > + return; > + > + if (!assigned) { > + /* > + * If all the pages are shared then no need to keep the RMP > + * and NPT in sync. > + */ > + pfn = pfn & ~(PTRS_PER_PMD - 1); > + if (is_pfn_range_shared(pfn, pfn + PTRS_PER_PMD)) > + return; > + } > + > + /* > + * The hardware installs 2MB TLB entries to access to 1GB pages, > + * therefore allow NPT to use 1GB pages when pfn was added as 2MB > + * in the RMP table. > + */ > + if (rmp_level == PG_LEVEL_2M && (*level == PG_LEVEL_1G)) > + return; > + > + /* Adjust the level to keep the NPT and RMP in sync */ > + *level = min_t(size_t, *level, rmp_level); > +} > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index b4bd64f94d3a..18e2cd4d9559 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -4734,6 +4734,7 @@ 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, > }; > > /* > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index 71c011af098e..7782312a1cda 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -673,6 +673,7 @@ 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); > +void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); > > /* vmenter.S */ > > -- > 2.25.1 > BR, Jarkko