Received-SPF: pass (google.com: domain of linux-kernel+bounces-13545-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.199.223 as permitted sender) client-ip=147.75.199.223;
Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C
From: Michael Roth <michael.roth@amd.com>
To: <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>, <vbabka@suse.cz>, <kirill@shutemov.name>,
	<ak@linux.intel.com>, <tony.luck@intel.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>
Subject: [PATCH v11 29/35] KVM: SEV: Implement gmem hook for invalidating private pages
Date: Sat, 30 Dec 2023 11:23:45 -0600
Message-ID: <20231230172351.574091-30-michael.roth@amd.com>
In-Reply-To: <20231230172351.574091-1-michael.roth@amd.com>
References: <20231230172351.574091-1-michael.roth@amd.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Dec 2023 17:32:00.0086
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: ce84035b-f920-46d0-7512-08dc095d3abc
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource:
	CO1PEPF000044EE.namprd05.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8211

Implement a platform hook to do the work of restoring the direct map
entries of gmem-managed pages and transitioning the corresponding RMP
table entries back to the default shared/hypervisor-owned state.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 arch/x86/kvm/Kconfig   |  1 +
 arch/x86/kvm/svm/sev.c | 63 ++++++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/svm/svm.c |  1 +
 arch/x86/kvm/svm/svm.h |  2 ++
 4 files changed, 67 insertions(+)

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 79c002e1bb5c..eb8a09f9341a 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -126,6 +126,7 @@ config KVM_AMD_SEV
 	depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m)
 	select KVM_GENERIC_PRIVATE_MEM
 	select HAVE_KVM_GMEM_PREPARE
+	select HAVE_KVM_GMEM_INVALIDATE
 	help
 	  Provides support for launching Encrypted VMs (SEV) and Encrypted VMs
 	  with Encrypted State (SEV-ES) on AMD processors.
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 91f53f4a6059..85f63b6842b6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -4252,3 +4252,66 @@ int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order)
 
 	return 0;
 }
+
+void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end)
+{
+	kvm_pfn_t pfn;
+
+	pr_debug("%s: PFN start 0x%llx PFN end 0x%llx\n", __func__, start, end);
+
+	for (pfn = start; pfn < end;) {
+		bool use_2m_update = false;
+		int rc, rmp_level;
+		bool assigned;
+
+		rc = snp_lookup_rmpentry(pfn, &assigned, &rmp_level);
+		if (rc) {
+			pr_debug_ratelimited("SEV: Failed to retrieve RMP entry for PFN 0x%llx error %d\n",
+					     pfn, rc);
+			goto next_pfn;
+		}
+
+		if (!assigned)
+			goto next_pfn;
+
+		use_2m_update = IS_ALIGNED(pfn, PTRS_PER_PMD) &&
+				end >= (pfn + PTRS_PER_PMD) &&
+				rmp_level > PG_LEVEL_4K;
+
+		/*
+		 * If an unaligned PFN corresponds to a 2M region assigned as a
+		 * large page in he RMP table, PSMASH the region into individual
+		 * 4K RMP entries before attempting to convert a 4K sub-page.
+		 */
+		if (!use_2m_update && rmp_level > PG_LEVEL_4K) {
+			rc = snp_rmptable_psmash(pfn);
+			if (rc)
+				pr_err_ratelimited("SEV: Failed to PSMASH RMP entry for PFN 0x%llx error %d\n",
+						   pfn, rc);
+		}
+
+		rc = rmp_make_shared(pfn, use_2m_update ? PG_LEVEL_2M : PG_LEVEL_4K);
+		if (WARN_ON_ONCE(rc)) {
+			pr_err_ratelimited("SEV: Failed to update RMP entry for PFN 0x%llx error %d\n",
+					   pfn, rc);
+			goto next_pfn;
+		}
+
+		/*
+		 * SEV-ES avoids host/guest cache coherency issues through
+		 * WBINVD hooks issued via MMU notifiers during run-time, and
+		 * KVM's VM destroy path at shutdown. Those MMU notifier events
+		 * don't cover gmem since there is no requirement to map pages
+		 * to a HVA in order to use them for a running guest. While the
+		 * shutdown path would still likely cover things for SNP guests,
+		 * userspace may also free gmem pages during run-time via
+		 * hole-punching operations on the guest_memfd, so flush the
+		 * cache entries for these pages before free'ing them back to
+		 * the host.
+		 */
+		clflush_cache_range(__va(pfn_to_hpa(pfn)),
+				    use_2m_update ? PMD_SIZE : PAGE_SIZE);
+next_pfn:
+		pfn += use_2m_update ? PTRS_PER_PMD : 1;
+	}
+}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 32cef8626b57..f26b8c2a8be4 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -5067,6 +5067,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.alloc_apic_backing_page = svm_alloc_apic_backing_page,
 
 	.gmem_prepare = sev_gmem_prepare,
+	.gmem_invalidate = sev_gmem_invalidate,
 };
 
 /*
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 9ece9612dbb9..a56109e100ac 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -726,6 +726,8 @@ struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu);
 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_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
+void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
+int sev_gmem_max_level(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, u8 *max_level);
 
 /* vmenter.S */
 
-- 
2.25.1