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Sampat" To: , , , CC: , , , , , , , , , , , Subject: [PATCH v3 1/2] mm/memory_hotplug: Add support to accept memory during hot-add Date: Wed, 28 Jan 2026 14:41:04 -0600 Message-ID: <20260128204105.508855-2-prsampat@amd.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260128204105.508855-1-prsampat@amd.com> References: <20260128204105.508855-1-prsampat@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY1PEPF0001AE17:EE_|SJ0PR12MB6710:EE_ X-MS-Office365-Filtering-Correlation-Id: 41a0cf5e-203a-4123-11f6-08de5ead99a2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|7416014|36860700013|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?G3Lfy/UjjUAuyOuBAgK1ClIc1mSHWG6G/YVjBEklL7kmH2/08cfN/26EHRk9?= =?us-ascii?Q?JJLUA9OfE3cuRPJ6nSjcfLxzCmMG/5DmniHr7laPTVz6sDDN7lwRpoZDmIaL?= =?us-ascii?Q?QpAdTtgloIJ9ZV+iW2C/zB9CiIlnymQpbA+HuqEe/kXZrmY9EfX7xvw03nuf?= =?us-ascii?Q?DO8Yu5RGfYKv4fbB0uwl7TA7jvKLFkEKa3tSvN79l5+kCyfP/rmKyShOR9Yf?= =?us-ascii?Q?9lj5pIC4dZyLfPAdQ21oi5SZY41Giubk9WpXmeNoWsBVUOOs2ti3gi9cVO/U?= =?us-ascii?Q?BQqrXyC6qO0Oo6xDuh6mus38+GJueNcl8VKXdWwbNjEwJtvi56y0aFf1VdE+?= =?us-ascii?Q?w86p5hYwG59naUIcHVm2HZX4MnP8R2rhmhGuMj7Kw7PS0q0mdugaT1/WRp4i?= =?us-ascii?Q?kLUjiqdIt+UzBhYA8N8PLHZz1F16xvDbrNvytQh7UbGfzsupHn4U3N1mJarp?= =?us-ascii?Q?OrvB8wEq+vepox9XXrnIie859ToF8MmbkEq03cl3obp5DYxoNW8n+gG7Z0qw?= =?us-ascii?Q?Fw3ZIijfemy7HecNiRhfT3YKBF9lOwM3yO6oCdugKUN/BOlsAs9G2KT6/gy7?= =?us-ascii?Q?2LvtvcScMnmRQIjrDB6mfy0mgp6ZnZFb91aXhYfbrRCcvyCo0r0yIXzl+9+u?= =?us-ascii?Q?WSzEvnM/4cRl2oupInVHWS6KqRpkXDUmc8mf+1+DNDN0gjILuQANMMiu+ebv?= =?us-ascii?Q?Ip3IXI6pdaJeLhkC8Wwz4h6djIWkMPVIS0U9I2XhFbgfwW1VT9oxHAEc9P/Q?= =?us-ascii?Q?P/KjT2kHhZUrFUOiFo97CBp3IUl8wyAVpPR2+Cq0fzCTZuLO/xDvgdUYBI++?= =?us-ascii?Q?REusK6quNjBbEtuFiUQ8ErOJ0e2V3umeEDUTuAbk6kXh3VutV5Jn5Y/OeXGG?= =?us-ascii?Q?772hUytNWidKDqRQMKoF6VUrf2mr50Crf/h2krYuxMaurCW4PtscscXUr27S?= =?us-ascii?Q?1yYeSs02twB1UBNtUZ9xLKsPjWngJYKFgxDXJmZKMBdDEvsfnWkhqs7MS3Jy?= =?us-ascii?Q?YGP/S9RHYaCETGAsfUhB6dLFYTBBV3LvehVpVCyl5jxaVrN3ZZ6K8VX2m/cm?= =?us-ascii?Q?mIaJq0+y3jAA2LcICsX6tLo/4JL6nIFTt4gWSRqIxyc6ZB+K8OGTFPbGTVBN?= =?us-ascii?Q?lthhDMobqZvucuocFta8GWZEKAhzZywI7ea9yHDTlvx/3LpeJTSHAHdgx4NJ?= =?us-ascii?Q?WZg2r3oyeyCtohxXyZ77UUZHcR0l+iujiv5D5EiwOd/CBhT2s51ZhqVLRB3d?= =?us-ascii?Q?qJ+FXnQ6dYI8qnCJp36VQg0wm52wRLPRBXiBw8XbFn8dooXHas2v0DvIPkGq?= =?us-ascii?Q?/rekHyxZx0MJcry6KhByXu13Pjo3KLTi/7/pDql5EUBRCKwwgMyYnqPD1hAr?= =?us-ascii?Q?e+dqR6O1lv1URa5nluYYYiTS+M7/dnpdozcx4RM4Idfwl89ssetoOdHIiavJ?= =?us-ascii?Q?90Ae3YaFsVfHQyp6lJzeQekrTFxb+z/Voa0ZnmeBVnRZ3dMfsYCqey8c8L2y?= =?us-ascii?Q?HNAGjbSDbgsLKXmBdVy/tcVzSBmEva5RbSlg/jDUKGBbi6b92ybhMIMHVzTU?= =?us-ascii?Q?8pkwhY1B6ohdp9aOk4nb6kilK7mRs+FhXnhDk2ERbFnAcyP1QuKa3S0nDQ7z?= =?us-ascii?Q?ucpoTGqp8wNU0qu6Kf9oIcIh5YSklxbeOdon2TALDZyCVoOD4REp0aHnKU5p?= =?us-ascii?Q?Dijnrw=3D=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(7416014)(36860700013)(376014);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Jan 2026 20:41:23.2230 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 41a0cf5e-203a-4123-11f6-08de5ead99a2 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BY1PEPF0001AE17.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB6710 Content-Type: text/plain; charset="utf-8" Confidential computing guests require memory to be accepted before use. The unaccepted memory bitmap maintained by firmware does not track most hotplugged memory ranges apart from system memory annotated to be cold plugged at boot. Explicitly validate and transition the newly added memory to a private state, making it usable by the guest. Signed-off-by: Pratik R. Sampat --- drivers/firmware/efi/unaccepted_memory.c | 18 ++++++++++++++++++ include/linux/mm.h | 5 +++++ mm/memory_hotplug.c | 2 ++ 3 files changed, 25 insertions(+) diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/ef= i/unaccepted_memory.c index c2c067eff634..5a4c8b0f56c8 100644 --- a/drivers/firmware/efi/unaccepted_memory.c +++ b/drivers/firmware/efi/unaccepted_memory.c @@ -209,6 +209,24 @@ bool range_contains_unaccepted_memory(phys_addr_t star= t, unsigned long size) return ret; } =20 +/* + * Unaccepted memory bitmap only covers initial boot memory and not the + * hotpluggable range that is part of SRAT parsing. However, some initial = memory + * with the attribute EFI_MEMORY_HOT_PLUGGABLE can indicate boot time memo= ry + * that can be hot-removed. Hence, handle acceptance in accordance with the + * unaccepted bitmap. Otherwise, perform the state change for the memory r= ange + * up-front. + */ +void accept_hotplug_memory(phys_addr_t start, unsigned long size) +{ + if (range_contains_unaccepted_memory(start, size)) { + accept_memory(start, size); + return; + } + + arch_accept_memory(start, start + size); +} + #ifdef CONFIG_PROC_VMCORE static bool unaccepted_memory_vmcore_pfn_is_ram(struct vmcore_cb *cb, unsigned long pfn) diff --git a/include/linux/mm.h b/include/linux/mm.h index 15076261d0c2..2d3c1ea40606 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4504,6 +4504,7 @@ int set_anon_vma_name(unsigned long addr, unsigned lo= ng size, =20 bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long siz= e); void accept_memory(phys_addr_t start, unsigned long size); +void accept_hotplug_memory(phys_addr_t start, unsigned long size); =20 #else =20 @@ -4517,6 +4518,10 @@ static inline void accept_memory(phys_addr_t start, = unsigned long size) { } =20 +static inline void accept_hotplug_memory(phys_addr_t start, unsigned long = size) +{ +} + #endif =20 static inline bool pfn_is_unaccepted_memory(unsigned long pfn) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index a63ec679d861..549ccfd190ee 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1567,6 +1567,8 @@ int add_memory_resource(int nid, struct resource *res= , mhp_t mhp_flags) if (!strcmp(res->name, "System RAM")) firmware_map_add_hotplug(start, start + size, "System RAM"); 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This also applies when memory is intended to be hotplugged back in later, as those pages will need to be re-accepted after crossing the trust boundary. Signed-off-by: Pratik R. Sampat --- arch/x86/coco/sev/core.c | 13 ++++++ arch/x86/include/asm/sev.h | 2 + arch/x86/include/asm/unaccepted_memory.h | 9 ++++ drivers/firmware/efi/unaccepted_memory.c | 56 ++++++++++++++++++++++++ include/linux/mm.h | 9 ++++ mm/memory_hotplug.c | 2 + 6 files changed, 91 insertions(+) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 9ae3b11754e6..63d8f44b76eb 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -703,6 +703,19 @@ void snp_accept_memory(phys_addr_t start, phys_addr_t = end) set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); } =20 +void snp_unaccept_memory(phys_addr_t start, phys_addr_t end) +{ + unsigned long vaddr, npages; + + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) + return; + + vaddr =3D (unsigned long)__va(start); + npages =3D (end - start) >> PAGE_SHIFT; + + set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); +} + static int vmgexit_ap_control(u64 event, struct sev_es_save_area *vmsa, u3= 2 apic_id) { bool create =3D event !=3D SVM_VMGEXIT_AP_DESTROY; diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 0e6c0940100f..3327de663793 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -514,6 +514,7 @@ bool snp_init(struct boot_params *bp); void snp_dmi_setup(void); int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct = svsm_attest_call *input); void snp_accept_memory(phys_addr_t start, phys_addr_t end); +void snp_unaccept_memory(phys_addr_t start, phys_addr_t end); u64 snp_get_unsupported_features(u64 status); u64 sev_get_status(void); void sev_show_status(void); @@ -623,6 +624,7 @@ static inline int snp_issue_svsm_attest_req(u64 call_id= , struct svsm_call *call, return -ENOTTY; } static inline void snp_accept_memory(phys_addr_t start, phys_addr_t end) {= } +static inline void snp_unaccept_memory(phys_addr_t start, phys_addr_t end)= { } static inline u64 snp_get_unsupported_features(u64 status) { return 0; } static inline u64 sev_get_status(void) { return 0; } static inline void sev_show_status(void) { } diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/as= m/unaccepted_memory.h index f5937e9866ac..8715be843e65 100644 --- a/arch/x86/include/asm/unaccepted_memory.h +++ b/arch/x86/include/asm/unaccepted_memory.h @@ -18,6 +18,15 @@ static inline void arch_accept_memory(phys_addr_t start,= phys_addr_t end) } } =20 +static inline void arch_unaccept_memory(phys_addr_t start, phys_addr_t end) +{ + if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) { + snp_unaccept_memory(start, end); + } else { + panic("Cannot unaccept memory: unknown platform\n"); + } +} + static inline struct efi_unaccepted_memory *efi_get_unaccepted_table(void) { if (efi.unaccepted =3D=3D EFI_INVALID_TABLE_ADDR) diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/ef= i/unaccepted_memory.c index 5a4c8b0f56c8..9f1d594dba33 100644 --- a/drivers/firmware/efi/unaccepted_memory.c +++ b/drivers/firmware/efi/unaccepted_memory.c @@ -157,6 +157,52 @@ void accept_memory(phys_addr_t start, unsigned long si= ze) spin_unlock_irqrestore(&unaccepted_memory_lock, flags); } =20 +void unaccept_memory(phys_addr_t start, unsigned long size) +{ + unsigned long range_start, range_end, bitrange_end; + struct efi_unaccepted_memory *unaccepted; + phys_addr_t end =3D start + size; + u64 unit_size, phys_base; + unsigned long flags; + + unaccepted =3D efi_get_unaccepted_table(); + if (!unaccepted) + return; + + phys_base =3D unaccepted->phys_base; + unit_size =3D unaccepted->unit_size; + + if (start < unaccepted->phys_base) + start =3D unaccepted->phys_base; + if (end < unaccepted->phys_base) + return; + + start -=3D phys_base; + end -=3D phys_base; + + /* Make sure not to overrun the bitmap */ + if (end > unaccepted->size * unit_size * BITS_PER_BYTE) + end =3D unaccepted->size * unit_size * BITS_PER_BYTE; + + range_start =3D start / unit_size; + bitrange_end =3D DIV_ROUND_UP(end, unit_size); + + /* Only unaccept memory that was previously accepted in the range */ + spin_lock_irqsave(&unaccepted_memory_lock, flags); + for_each_clear_bitrange_from(range_start, range_end, unaccepted->bitmap, + bitrange_end) { + unsigned long phys_start, phys_end; + unsigned long len =3D range_end - range_start; + + phys_start =3D range_start * unit_size + phys_base; + phys_end =3D range_end * unit_size + phys_base; + + arch_unaccept_memory(phys_start, phys_end); + bitmap_set(unaccepted->bitmap, range_start, len); + } + spin_unlock_irqrestore(&unaccepted_memory_lock, flags); +} + bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long siz= e) { struct efi_unaccepted_memory *unaccepted; @@ -227,6 +273,16 @@ void accept_hotplug_memory(phys_addr_t start, unsigned= long size) arch_accept_memory(start, start + size); } =20 +void unaccept_hotplug_memory(phys_addr_t start, unsigned long size) +{ + if (range_contains_unaccepted_memory(start, size)) { + unaccept_memory(start, size); + return; + } + + arch_unaccept_memory(start, start + size); +} + #ifdef CONFIG_PROC_VMCORE static bool unaccepted_memory_vmcore_pfn_is_ram(struct vmcore_cb *cb, unsigned long pfn) diff --git a/include/linux/mm.h b/include/linux/mm.h index 2d3c1ea40606..faefaa9b92c6 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4504,7 +4504,9 @@ int set_anon_vma_name(unsigned long addr, unsigned lo= ng size, =20 bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long siz= e); void accept_memory(phys_addr_t start, unsigned long size); +void unaccept_memory(phys_addr_t start, unsigned long size); void accept_hotplug_memory(phys_addr_t start, unsigned long size); +void unaccept_hotplug_memory(phys_addr_t start, unsigned long size); =20 #else =20 @@ -4518,10 +4520,17 @@ static inline void accept_memory(phys_addr_t start,= unsigned long size) { } =20 +static inline void unaccept_memory(phys_addr_t start, unsigned long size) +{ +} + static inline void accept_hotplug_memory(phys_addr_t start, unsigned long = size) { } =20 +static inline void unaccept_hotplug_memory(phys_addr_t start, unsigned lon= g size) +{ +} #endif =20 static inline bool pfn_is_unaccepted_memory(unsigned long pfn) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 549ccfd190ee..21b87f2af930 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -2240,6 +2240,8 @@ static int try_remove_memory(u64 start, u64 size) =20 mem_hotplug_begin(); =20 + unaccept_hotplug_memory(start, size); + rc =3D memory_blocks_have_altmaps(start, size); if (rc < 0) { mem_hotplug_done(); --=20 2.52.0