From: Rick Edgecombe Implement a PAMT "caching" scheme, similar to KVM's pre-allocated cache of MMU assets, along with APIs to allow KVM to pre-allocate PAMT pages before acquiring its mmu_lock spinlock, but wait until S-EPT entries are created to actually update the Dynamic PAMT. Signed-off-by: Rick Edgecombe Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- arch/x86/include/asm/tdx.h | 17 ++++++++++ arch/x86/virt/vmx/tdx/tdx.c | 65 +++++++++++++++++++++++++++++++++---- 2 files changed, 76 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index fa29be18498c..c39e2920d0c3 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -136,6 +136,23 @@ static inline bool tdx_supports_dynamic_pamt(const struct tdx_sys_info *sysinfo) return false; /* To be enabled when kernel is ready */ } +/* Simple structure for pre-allocating Dynamic PAMT pages outside of locks. */ +struct tdx_pamt_cache { + struct list_head page_list; + int cnt; +}; + +static inline void tdx_init_pamt_cache(struct tdx_pamt_cache *cache) +{ + INIT_LIST_HEAD(&cache->page_list); + cache->cnt = 0; +} + +void tdx_free_pamt_cache(struct tdx_pamt_cache *cache); +int tdx_topup_pamt_cache(struct tdx_pamt_cache *cache, unsigned long npages); +int tdx_pamt_get(struct page *page, struct tdx_pamt_cache *cache); +void tdx_pamt_put(struct page *page); + void tdx_quirk_reset_page(struct page *page); int tdx_guest_keyid_alloc(void); diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index d333d2790913..53b29c827520 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -2064,13 +2064,34 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page) } EXPORT_SYMBOL_FOR_KVM(tdh_phymem_page_wbinvd_hkid); -static int alloc_pamt_array(u64 *pa_array) +static struct page *tdx_alloc_page_pamt_cache(struct tdx_pamt_cache *cache) +{ + struct page *page; + + page = list_first_entry_or_null(&cache->page_list, struct page, lru); + if (page) { + list_del(&page->lru); + cache->cnt--; + } + + return page; +} + +static struct page *alloc_dpamt_page(struct tdx_pamt_cache *cache) +{ + if (cache) + return tdx_alloc_page_pamt_cache(cache); + + return alloc_page(GFP_KERNEL_ACCOUNT); +} + +static int alloc_pamt_array(u64 *pa_array, struct tdx_pamt_cache *cache) { struct page *page; int i; for (i = 0; i < tdx_dpamt_entry_pages(); i++) { - page = alloc_page(GFP_KERNEL_ACCOUNT); + page = alloc_dpamt_page(cache); if (!page) goto err; pa_array[i] = page_to_phys(page); @@ -2151,7 +2172,7 @@ static u64 tdh_phymem_pamt_remove(struct page *page, u64 *pamt_pa_array) static DEFINE_SPINLOCK(pamt_lock); /* Bump PAMT refcount for the given page and allocate PAMT memory if needed */ -static int tdx_pamt_get(struct page *page) +int tdx_pamt_get(struct page *page, struct tdx_pamt_cache *cache) { u64 pamt_pa_array[MAX_NR_DPAMT_ARGS]; atomic_t *pamt_refcount; @@ -2170,7 +2191,7 @@ static int tdx_pamt_get(struct page *page) if (atomic_inc_not_zero(pamt_refcount)) return 0; - ret = alloc_pamt_array(pamt_pa_array); + ret = alloc_pamt_array(pamt_pa_array, cache); if (ret) goto out_free; @@ -2222,12 +2243,13 @@ static int tdx_pamt_get(struct page *page) free_pamt_array(pamt_pa_array); return ret; } +EXPORT_SYMBOL_FOR_KVM(tdx_pamt_get); /* * Drop PAMT refcount for the given page and free PAMT memory if it is no * longer needed. */ -static void tdx_pamt_put(struct page *page) +void tdx_pamt_put(struct page *page) { u64 pamt_pa_array[MAX_NR_DPAMT_ARGS]; atomic_t *pamt_refcount; @@ -2281,6 +2303,37 @@ static void tdx_pamt_put(struct page *page) */ free_pamt_array(pamt_pa_array); } +EXPORT_SYMBOL_FOR_KVM(tdx_pamt_put); + +void tdx_free_pamt_cache(struct tdx_pamt_cache *cache) +{ + struct page *page; + + while ((page = tdx_alloc_page_pamt_cache(cache))) + __free_page(page); +} +EXPORT_SYMBOL_FOR_KVM(tdx_free_pamt_cache); + +int tdx_topup_pamt_cache(struct tdx_pamt_cache *cache, unsigned long npages) +{ + if (WARN_ON_ONCE(!tdx_supports_dynamic_pamt(&tdx_sysinfo))) + return 0; + + npages *= tdx_dpamt_entry_pages(); + + while (cache->cnt < npages) { + struct page *page = alloc_page(GFP_KERNEL_ACCOUNT); + + if (!page) + return -ENOMEM; + + list_add(&page->lru, &cache->page_list); + cache->cnt++; + } + + return 0; +} +EXPORT_SYMBOL_FOR_KVM(tdx_topup_pamt_cache); /* * Return a page that can be gifted to the TDX-Module for use as a "control" @@ -2296,7 +2349,7 @@ struct page *__tdx_alloc_control_page(gfp_t gfp) if (!page) return NULL; - if (tdx_pamt_get(page)) { + if (tdx_pamt_get(page, NULL)) { __free_page(page); return NULL; } -- 2.53.0.rc1.217.geba53bf80e-goog