There are few issues/bugs in the deposit memory implementation: o It is very slow o Contiguous range requirement is ignored, and is critical bug o An incorrect assumption is made that contiguous memory size would always be power of 2. o Two pages are allocated, only one is really needed. This adds to overhead. o For a 512 page deposit, the allocation is split into two: one for 511 and second for 1. Thus, an order 9 allocation never happens. A contiguous 2M range would significantly improve performance in the hypervisor. o Since a page is already allocated to collect the frames, there is not really a need to use per cpu input page, and hence avoid local irq disable.
All of above is addressed by: o Start with a full 2M range alloc, thus getting contiguous if available. o Allocate only one page in the deposit function and collect 511 pfns there. Just use a local variable for last pfn. o Use the page as input to hypercall. Since this page is allocated, irq disable can be avoided helping speed up the deposit. o Fix the contiguous requirement by using kmalloc in such case. o A minimum deposit of 2M done universally to overcome bad performance overheads. The hypervisor will always first reuse any unused memory that was previously deposited before asking for more. Signed-off-by: Mukesh R <[email protected]> --- drivers/hv/hv_proc.c | 180 +++++++++++++++++++++++++++++++-- drivers/hv/mshv_root_hv_call.c | 10 +- include/asm-generic/mshyperv.h | 5 - 3 files changed, 174 insertions(+), 21 deletions(-) diff --git a/drivers/hv/hv_proc.c b/drivers/hv/hv_proc.c index d5ce9a032e9c..fd74c286e612 100644 --- a/drivers/hv/hv_proc.c +++ b/drivers/hv/hv_proc.c @@ -9,15 +9,182 @@ #include <linux/export.h> #include <asm/mshyperv.h> -int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages) +#define HV_DEPOSIT_MAX 512 +#define HV_DEPOSIT_INP_MAX ((HV_HYP_PAGE_SIZE - \ + offsetof(struct hv_deposit_memory, gpa_page_list)) / sizeof(u64)) + +static int hv_alloc_contig_pages(int node, u64 *pfna, u64 *lastpfnp, + int num_pages) +{ + void *p; + int i, tmp; + ulong pfn; + size_t size = num_pages * HV_HYP_PAGE_SIZE; + + if (num_pages > HV_DEPOSIT_MAX || + (num_pages == HV_DEPOSIT_MAX && lastpfnp == NULL)) + return -EINVAL; + + p = kmalloc_node(size, GFP_KERNEL, node); + if (p == NULL) + return -ENOMEM; + + pfn = PFN_DOWN(virt_to_phys(p)); + tmp = min(num_pages, HV_DEPOSIT_INP_MAX); + + for (i = 0; i < tmp; i++, pfn++) + pfna[i] = pfn; + + if (num_pages == HV_DEPOSIT_MAX) + *lastpfnp = pfn; + + return num_pages; +} + + +/* + * Allocate free pages for deposit to hypervisor. pfna[] must be large enough + * to hold HV_DEPOSIT_INP_MAX (511) pages. If num_pages is 512, return last + * pfn in lastpfn. + * + * Returns : -ENOMEM if zero allocated, else number of pages allocated + */ +static int hv_alloc_dep_pages(int node, u64 *pfna, u64 *lastpfnp, int num_pages) +{ + struct page *page; + int num_allocd, count = 0; + + /* Published ABI, enforce its immutability. */ + BUILD_BUG_ON(HV_DEPOSIT_INP_MAX != 511); + + if (num_pages > HV_DEPOSIT_MAX || + (num_pages == HV_DEPOSIT_MAX && lastpfnp == NULL)) + return -EINVAL; + + while (num_pages) { + /* Find highest order we can actually allocate */ + int order = 31 - __builtin_clz(num_pages); + + while (1) { + page = alloc_pages_node(node, GFP_KERNEL, order); + if (page || order == 0) + break; + + order--; + } + + if (page == NULL) + break; + + split_page(page, order); + num_allocd = 1 << order; + num_pages -= num_allocd; + + while (num_allocd && count < HV_DEPOSIT_INP_MAX) { + pfna[count++] = page_to_pfn(page++); + num_allocd--; + } + + if (num_allocd-- && count == HV_DEPOSIT_INP_MAX) { + *lastpfnp = page_to_pfn(page); + count++; + break; + } + } + + return count ? count : -ENOMEM; +} + +/* + * Deposit memory in the hypervisor. A contiguous 2M worth of pfns is utmost + * desired, but short of that, we deposit whatever contiguous chunks we can + * get. + */ +static int hv_call_deposit_memory(int node, u64 partition_id, bool contiguous) { - return -ENOTSUPP; + struct hv_deposit_memory *hc_input; + int i, rc, num_pages; + u64 status, *pfna, lastpfn = 0; + + BUILD_BUG_ON(HV_MAX_CONTIGUOUS_ALLOCATION_PAGES > HV_DEPOSIT_MAX); + + if (contiguous) + num_pages = HV_MAX_CONTIGUOUS_ALLOCATION_PAGES; + else + num_pages = HV_DEPOSIT_MAX; + + hc_input = (struct hv_deposit_memory *)get_zeroed_page(GFP_KERNEL); + if (hc_input == NULL) + return -ENOMEM; + + hc_input->partition_id = partition_id; + pfna = hc_input->gpa_page_list; + + if (contiguous) + rc = hv_alloc_contig_pages(node, pfna, &lastpfn, num_pages); + else + rc = hv_alloc_dep_pages(node, pfna, &lastpfn, num_pages); + if (rc < 0) + goto out_free; + + num_pages = rc; + if (num_pages > HV_DEPOSIT_INP_MAX) + num_pages = HV_DEPOSIT_INP_MAX; + + /* We are not using hyperv_pcpu_input_arg, so no need to disable */ + + status = hv_do_rep_hypercall(HVCALL_DEPOSIT_MEMORY, num_pages, + 0, hc_input, NULL); + if (!hv_result_success(status)) { + hv_status_err(status, "\n"); + rc = hv_result_to_errno(status); + goto out_free_dep_pages; + } + + if (lastpfn) { + hc_input->gpa_page_list[0] = lastpfn; + status = hv_do_rep_hypercall(HVCALL_DEPOSIT_MEMORY, 1, 0, + hc_input, NULL); + if (!hv_result_success(status)) + /* We deposited some earlier, so just free this */ + __free_page(pfn_to_page(lastpfn)); + } + + free_page((unsigned long)hc_input); + return 0; + +out_free_dep_pages: + for (i = 0; i < num_pages; i++) + __free_page(pfn_to_page(pfna[i])); + if (lastpfn) + __free_page(pfn_to_page(lastpfn)); + +out_free: + free_page((unsigned long)hc_input); + return rc; } -EXPORT_SYMBOL_GPL(hv_call_deposit_pages); -int hv_deposit_memory_node(int node, u64 partition_id, u64 hv_status) +int hv_deposit_memory_node(int node, u64 pt_id, u64 hv_status) { - return -ENOTSUPP; + int result = hv_result(hv_status); + bool contiguous = false; + + if (result == HV_STATUS_INSUFFICIENT_ROOT_MEMORY || + result == HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY) { + if (!hv_root_partition()) { + hv_status_err(hv_status, + "Unexpected root memory deposit\n"); + return -EINVAL; + } + + pt_id = HV_PARTITION_ID_SELF; + } + + if (result == HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY || + result == HV_STATUS_INSUFFICIENT_CONTIGUOUS_ROOT_MEMORY) + contiguous = true; + + return hv_call_deposit_memory(node, pt_id, contiguous); } EXPORT_SYMBOL_GPL(hv_deposit_memory_node); @@ -85,8 +252,7 @@ int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags) /* Root VPs don't seem to need pages deposited */ if (partition_id != hv_current_partition_id) { - /* The value 90 is empirically determined. It may change. */ - ret = hv_call_deposit_pages(node, partition_id, 90); + ret = hv_call_deposit_memory(node, partition_id, false); if (ret) return ret; } diff --git a/drivers/hv/mshv_root_hv_call.c b/drivers/hv/mshv_root_hv_call.c index cb55d4d4be2e..b8d199f95299 100644 --- a/drivers/hv/mshv_root_hv_call.c +++ b/drivers/hv/mshv_root_hv_call.c @@ -15,8 +15,6 @@ #include "mshv_root.h" /* Determined empirically */ -#define HV_INIT_PARTITION_DEPOSIT_PAGES 208 -#define HV_MAP_GPA_DEPOSIT_PAGES 256 #define HV_UMAP_GPA_PAGES 512 #define HV_PAGE_COUNT_2M_ALIGNED(pg_count) (!((pg_count) & (0x200 - 1))) @@ -140,11 +138,6 @@ int hv_call_initialize_partition(u64 partition_id) input.partition_id = partition_id; - ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id, - HV_INIT_PARTITION_DEPOSIT_PAGES); - if (ret) - return ret; - do { status = hv_do_fast_hypercall8(HVCALL_INITIALIZE_PARTITION, *(u64 *)&input); @@ -248,8 +241,7 @@ static int hv_do_map_gpa_hcall(u64 partition_id, u64 gfn, u64 page_struct_count, completed = hv_repcomp(status); if (hv_result_needs_memory(status)) { - ret = hv_call_deposit_pages(NUMA_NO_NODE, partition_id, - HV_MAP_GPA_DEPOSIT_PAGES); + ret = hv_deposit_memory(partition_id, status); if (ret) break; diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index bf601d67cecb..c16abaecb65e 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -345,7 +345,6 @@ static inline bool hv_parent_partition(void) bool hv_result_needs_memory(u64 status); int hv_deposit_memory_node(int node, u64 partition_id, u64 status); -int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages); int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id); int hv_call_notify_all_processors_started(void); bool hv_lp_exists(u32 lp_index); @@ -360,10 +359,6 @@ static inline int hv_deposit_memory_node(int node, u64 partition_id, u64 status) { return -EOPNOTSUPP; } -static inline int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages) -{ - return -EOPNOTSUPP; -} static inline int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id) { return -EOPNOTSUPP; -- 2.51.2.vfs.0.1
