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([2404:f801:9000:18:efec::50b]) by smtp.gmail.com with ESMTPSA id q32sm2126609pja.4.2021.12.03.03.20.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Dec 2021 03:20:17 -0800 (PST) Message-ID: Date: Fri, 3 Dec 2021 19:20:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH V3 1/5] Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM Content-Language: en-US To: Tom Lendacky , kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jgross@suse.com, sstabellini@kernel.org, boris.ostrovsky@oracle.com, joro@8bytes.org, will@kernel.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, hch@infradead.org, m.szyprowski@samsung.com, robin.murphy@arm.com, Tianyu.Lan@microsoft.com, xen-devel@lists.xenproject.org, michael.h.kelley@microsoft.com Cc: iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, vkuznets@redhat.com, brijesh.singh@amd.com, konrad.wilk@oracle.com, hch@lst.de, parri.andrea@gmail.com, dave.hansen@intel.com References: <20211201160257.1003912-1-ltykernel@gmail.com> <20211201160257.1003912-2-ltykernel@gmail.com> <41bb0a87-9fdb-4c67-a903-9e87d092993a@amd.com> From: Tianyu Lan In-Reply-To: <41bb0a87-9fdb-4c67-a903-9e87d092993a@amd.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/2/2021 10:42 PM, Tom Lendacky wrote: > On 12/1/21 10:02 AM, Tianyu Lan wrote: >> From: Tianyu Lan >> >> In Isolation VM with AMD SEV, bounce buffer needs to be accessed via >> extra address space which is above shared_gpa_boundary (E.G 39 bit >> address line) reported by Hyper-V CPUID ISOLATION_CONFIG. The access >> physical address will be original physical address + shared_gpa_boundary. >> The shared_gpa_boundary in the AMD SEV SNP spec is called virtual top of >> memory(vTOM). Memory addresses below vTOM are automatically treated as >> private while memory above vTOM is treated as shared. >> >> Expose swiotlb_unencrypted_base for platforms to set unencrypted >> memory base offset and platform calls swiotlb_update_mem_attributes() >> to remap swiotlb mem to unencrypted address space. memremap() can >> not be called in the early stage and so put remapping code into >> swiotlb_update_mem_attributes(). Store remap address and use it to copy >> data from/to swiotlb bounce buffer. >> >> Signed-off-by: Tianyu Lan > > This patch results in the following stack trace during a bare-metal boot > on my EPYC system with SME active (e.g. mem_encrypt=on): > > [    0.123932] BUG: Bad page state in process swapper  pfn:108001 > [    0.123942] page:(____ptrval____) refcount:0 mapcount:-128 > mapping:0000000000000000 index:0x0 pfn:0x108001 > [    0.123946] flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) > [    0.123952] raw: 0017ffffc0000000 ffff88904f2d5e80 ffff88904f2d5e80 > 0000000000000000 > [    0.123954] raw: 0000000000000000 0000000000000000 00000000ffffff7f > 0000000000000000 > [    0.123955] page dumped because: nonzero mapcount > [    0.123957] Modules linked in: > [    0.123961] CPU: 0 PID: 0 Comm: swapper Not tainted > 5.16.0-rc3-sos-custom #2 > [    0.123964] Hardware name: AMD Corporation > [    0.123967] Call Trace: > [    0.123971]  > [    0.123975]  dump_stack_lvl+0x48/0x5e > [    0.123985]  bad_page.cold+0x65/0x96 > [    0.123990]  __free_pages_ok+0x3a8/0x410 > [    0.123996]  memblock_free_all+0x171/0x1dc > [    0.124005]  mem_init+0x1f/0x14b > [    0.124011]  start_kernel+0x3b5/0x6a1 > [    0.124016]  secondary_startup_64_no_verify+0xb0/0xbb > [    0.124022]  > > I see ~40 of these traces, each for different pfns. > > Thanks, > Tom Hi Tom: Thanks for your test. Could you help to test the following patch and check whether it can fix the issue. diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 569272871375..f6c3638255d5 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -73,6 +73,9 @@ extern enum swiotlb_force swiotlb_force; * @end: The end address of the swiotlb memory pool. Used to do a quick * range check to see if the memory was in fact allocated by this * API. + * @vaddr: The vaddr of the swiotlb memory pool. The swiotlb memory pool + * may be remapped in the memory encrypted case and store virtual + * address for bounce buffer operation. * @nslabs: The number of IO TLB blocks (in groups of 64) between @start and * @end. For default swiotlb, this is command line adjustable via * setup_io_tlb_npages. @@ -92,6 +95,7 @@ extern enum swiotlb_force swiotlb_force; struct io_tlb_mem { phys_addr_t start; phys_addr_t end; + void *vaddr; unsigned long nslabs; unsigned long used; unsigned int index; @@ -186,4 +190,6 @@ static inline bool is_swiotlb_for_alloc(struct device *dev) } #endif /* CONFIG_DMA_RESTRICTED_POOL */ +extern phys_addr_t swiotlb_unencrypted_base; + #endif /* __LINUX_SWIOTLB_H */ diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 8e840fbbed7c..34e6ade4f73c 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -50,6 +50,7 @@ #include #include +#include #include #include #include @@ -72,6 +73,8 @@ enum swiotlb_force swiotlb_force; struct io_tlb_mem io_tlb_default_mem; +phys_addr_t swiotlb_unencrypted_base; + /* * Max segment that we can provide which (if pages are contingous) will * not be bounced (unless SWIOTLB_FORCE is set). @@ -155,6 +158,27 @@ static inline unsigned long nr_slots(u64 val) return DIV_ROUND_UP(val, IO_TLB_SIZE); } +/* + * Remap swioltb memory in the unencrypted physical address space + * when swiotlb_unencrypted_base is set. (e.g. for Hyper-V AMD SEV-SNP + * Isolation VMs). + */ +void *swiotlb_mem_remap(struct io_tlb_mem *mem, unsigned long bytes) +{ + void *vaddr = NULL; + + if (swiotlb_unencrypted_base) { + phys_addr_t paddr = mem->start + swiotlb_unencrypted_base; + + vaddr = memremap(paddr, bytes, MEMREMAP_WB); + if (!vaddr) + pr_err("Failed to map the unencrypted memory %llx size %lx.\n", + paddr, bytes); + } + + return vaddr; +} + /* * Early SWIOTLB allocation may be too early to allow an architecture to * perform the desired operations. This function allows the architecture to @@ -172,7 +196,12 @@ void __init swiotlb_update_mem_attributes(void) vaddr = phys_to_virt(mem->start); bytes = PAGE_ALIGN(mem->nslabs << IO_TLB_SHIFT); set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT); - memset(vaddr, 0, bytes); + + mem->vaddr = swiotlb_mem_remap(mem, bytes); + if (!mem->vaddr) + mem->vaddr = vaddr; + + memset(mem->vaddr, 0, bytes); } static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start, @@ -196,7 +225,17 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start, mem->slots[i].orig_addr = INVALID_PHYS_ADDR; mem->slots[i].alloc_size = 0; } + + /* + * If swiotlb_unencrypted_base is set, the bounce buffer memory will + * be remapped and cleared in swiotlb_update_mem_attributes. + */ + if (swiotlb_unencrypted_base) + return; + memset(vaddr, 0, bytes); + mem->vaddr = vaddr; + return; } int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose) @@ -371,7 +410,7 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size phys_addr_t orig_addr = mem->slots[index].orig_addr; size_t alloc_size = mem->slots[index].alloc_size; unsigned long pfn = PFN_DOWN(orig_addr); - unsigned char *vaddr = phys_to_virt(tlb_addr); + unsigned char *vaddr = mem->vaddr + tlb_addr - mem->start; unsigned int tlb_offset, orig_addr_offset; if (orig_addr == INVALID_PHYS_ADDR) Thanks.