Transition memory to the shared state during a hot-remove operation so that it can be re-used by the hypervisor. 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 | 15 ++++++ drivers/firmware/efi/unaccepted_memory.c | 59 ++++++++++++++++++++++++ include/linux/mm.h | 4 ++ mm/memory_hotplug.c | 2 + 6 files changed, 95 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); } +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 = (unsigned long)__va(start); + npages = (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, u32 apic_id) { bool create = event != 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/asm/unaccepted_memory.h index f5937e9866ac..91f01ad0ee03 100644 --- a/arch/x86/include/asm/unaccepted_memory.h +++ b/arch/x86/include/asm/unaccepted_memory.h @@ -18,6 +18,21 @@ static inline void arch_accept_memory(phys_addr_t start, phys_addr_t end) } } +static inline void arch_unaccept_memory(phys_addr_t start, phys_addr_t end) +{ + /* + * TDX platforms do not require the guest to transition pages on remove + * rather expect the VMM to remove the unplugged memory from SEPT + */ + if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) { + return; + } else 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 == EFI_INVALID_TABLE_ADDR) diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c index 359779133cb4..d11e7836200a 100644 --- a/drivers/firmware/efi/unaccepted_memory.c +++ b/drivers/firmware/efi/unaccepted_memory.c @@ -256,6 +256,65 @@ void accept_hotplug_memory(phys_addr_t start, unsigned long size) spin_unlock_irqrestore(&unaccepted_memory_lock, flags); } +/* + * Cold-plugged memory used with lazy acceptance may partially set pages to + * private. On removal, iterate through the bitmap to unaccept those ranges. + * For hotplug ranges beyond the bitmap, unaccept unconditionally. + */ +void unaccept_hotplug_memory(phys_addr_t start, unsigned long size) +{ + unsigned long range_start, range_end, bitrange_end; + phys_addr_t bitmap_end, end = start + size; + struct efi_unaccepted_memory *unaccepted; + u64 phys_base, unit_size; + unsigned long flags; + + unaccepted = efi_get_unaccepted_table(); + if (!unaccepted) + return; + + phys_base = unaccepted->phys_base; + unit_size = unaccepted->unit_size; + bitmap_end = phys_base + unaccepted->size * unit_size * BITS_PER_BYTE; + + /* Unaccept the entire hotplug range beyond the bitmap immediately */ + if (start >= bitmap_end) { + arch_unaccept_memory(start, end); + return; + } + + start = max(start, phys_base); + if (end < phys_base) + return; + + /* Unaccept ranges when start is within the bitmap but end is beyond */ + if (end > bitmap_end) { + arch_unaccept_memory(bitmap_end, end); + end = bitmap_end; + } + + start -= phys_base; + end -= phys_base; + + range_start = start / unit_size; + bitrange_end = DIV_ROUND_UP(end, unit_size); + + /* Only unaccept memory that was previously accepted in the bitmap */ + 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 = range_end - range_start; + + phys_start = range_start * unit_size + phys_base; + phys_end = 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); +} + #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..49b194cddda7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4505,6 +4505,7 @@ int set_anon_vma_name(unsigned long addr, unsigned long size, bool range_contains_unaccepted_memory(phys_addr_t start, unsigned long size); void accept_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); #else @@ -4522,6 +4523,9 @@ static inline void accept_hotplug_memory(phys_addr_t start, unsigned long size) { } +static inline void unaccept_hotplug_memory(phys_addr_t start, unsigned long size) +{ +} #endif 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) mem_hotplug_begin(); + unaccept_hotplug_memory(start, size); + rc = memory_blocks_have_altmaps(start, size); if (rc < 0) { mem_hotplug_done(); -- 2.52.0