From: "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To: Tianyu Lan <ltykernel@gmail.com>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"wei.liu@kernel.org" <wei.liu@kernel.org>,
Dexuan Cui <decui@microsoft.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"hpa@zytor.com" <hpa@zytor.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"kuba@kernel.org" <kuba@kernel.org>,
"jejb@linux.ibm.com" <jejb@linux.ibm.com>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"arnd@arndb.de" <arnd@arndb.de>,
"hch@infradead.org" <hch@infradead.org>,
"m.szyprowski@samsung.com" <m.szyprowski@samsung.com>,
"robin.murphy@arm.com" <robin.murphy@arm.com>,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
"thomas.lendacky@amd.com" <thomas.lendacky@amd.com>
Cc: "iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
vkuznets <vkuznets@redhat.com>,
"brijesh.singh@amd.com" <brijesh.singh@amd.com>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
"hch@lst.de" <hch@lst.de>, "joro@8bytes.org" <joro@8bytes.org>,
"parri.andrea@gmail.com" <parri.andrea@gmail.com>,
"dave.hansen@intel.com" <dave.hansen@intel.com>
Subject: RE: [PATCH V6 3/5] hyper-v: Enable swiotlb bounce buffer for Isolation VM
Date: Thu, 9 Dec 2021 20:09:18 +0000 [thread overview]
Message-ID: <MWHPR21MB159359667085776793988EACD7709@MWHPR21MB1593.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20211207075602.2452-4-ltykernel@gmail.com>
From: Tianyu Lan <ltykernel@gmail.com> Sent: Monday, December 6, 2021 11:56 PM
>
> hyperv Isolation VM requires bounce buffer support to copy
> data from/to encrypted memory and so enable swiotlb force
> mode to use swiotlb bounce buffer for DMA transaction.
>
> In Isolation VM with AMD SEV, the 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.
>
> Swiotlb bounce buffer code calls set_memory_decrypted()
> to mark bounce buffer visible to host and map it in extra
> address space via memremap. Populate the shared_gpa_boundary
> (vTOM) via swiotlb_unencrypted_base variable.
>
> The map function memremap() can't work in the early place
> (e.g ms_hyperv_init_platform()) and so call swiotlb_update_mem_
> attributes() in the hyperv_init().
>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
> ---
> Change since v4:
> * Remove Hyper-V IOMMU IOMMU_INIT_FINISH related functions
> and set SWIOTLB_FORCE and swiotlb_unencrypted_base in the
> ms_hyperv_init_platform(). Call swiotlb_update_mem_attributes()
> in the hyperv_init().
>
> Change since v3:
> * Add comment in pci-swiotlb-xen.c to explain why add
> dependency between hyperv_swiotlb_detect() and pci_
> xen_swiotlb_detect().
> * Return directly when fails to allocate Hyper-V swiotlb
> buffer in the hyperv_iommu_swiotlb_init().
> ---
> arch/x86/hyperv/hv_init.c | 10 ++++++++++
> arch/x86/kernel/cpu/mshyperv.c | 11 ++++++++++-
> include/linux/hyperv.h | 8 ++++++++
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 24f4a06ac46a..9e18a280f89d 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -28,6 +28,7 @@
> #include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
> #include <linux/highmem.h>
> +#include <linux/swiotlb.h>
>
> int hyperv_init_cpuhp;
> u64 hv_current_partition_id = ~0ull;
> @@ -502,6 +503,15 @@ void __init hyperv_init(void)
>
> /* Query the VMs extended capability once, so that it can be cached. */
> hv_query_ext_cap(0);
> +
> + /*
> + * Swiotlb bounce buffer needs to be mapped in extra address
> + * space. Map function doesn't work in the early place and so
> + * call swiotlb_update_mem_attributes() here.
> + */
> + if (hv_is_isolation_supported())
> + swiotlb_update_mem_attributes();
> +
> return;
>
> clean_guest_os_id:
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 4794b716ec79..baf3a0873552 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -18,6 +18,7 @@
> #include <linux/kexec.h>
> #include <linux/i8253.h>
> #include <linux/random.h>
> +#include <linux/swiotlb.h>
> #include <asm/processor.h>
> #include <asm/hypervisor.h>
> #include <asm/hyperv-tlfs.h>
> @@ -319,8 +320,16 @@ static void __init ms_hyperv_init_platform(void)
> pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
> ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
>
> - if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
> + if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
> static_branch_enable(&isolation_type_snp);
> + swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
> + }
> +
> + /*
> + * Enable swiotlb force mode in Isolation VM to
> + * use swiotlb bounce buffer for dma transaction.
> + */
> + swiotlb_force = SWIOTLB_FORCE;
I'm good with this approach that directly updates the swiotlb settings here
rather than in IOMMU initialization code. It's a lot more straightforward.
However, there's an issue if building for X86_32 without PAE, in that the
swiotlb module may not be built, resulting in compile and link errors. The
swiotlb.h file needs to be updated to provide a stub function for
swiotlb_update_mem_attributes(). swiotlb_unencrypted_base probably
needs wrapper functions to get/set it, which can be stubs when
CONFIG_SWIOTLB is not set. swiotlb_force is a bit of a mess in that it already
has a stub definition that assumes it will only be read, and not set. A bit of
thinking will be needed to sort that out.
> }
>
> if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index b823311eac79..1f037e114dc8 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1726,6 +1726,14 @@ int hyperv_write_cfg_blk(struct pci_dev *dev, void *buf, unsigned int len,
> int hyperv_reg_block_invalidate(struct pci_dev *dev, void *context,
> void (*block_invalidate)(void *context,
> u64 block_mask));
> +#if IS_ENABLED(CONFIG_HYPERV)
> +int __init hyperv_swiotlb_detect(void);
> +#else
> +static inline int __init hyperv_swiotlb_detect(void)
> +{
> + return 0;
> +}
> +#endif
I don't think hyperv_swiotlb_detect() is used any longer, so this change
should be dropped.
>
> struct hyperv_pci_block_ops {
> int (*read_block)(struct pci_dev *dev, void *buf, unsigned int buf_len,
> --
> 2.25.1
next prev parent reply other threads:[~2021-12-09 20:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 7:55 [PATCH V6 0/5] x86/Hyper-V: Add Hyper-V Isolation VM support(Second part) Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 1/5] swiotlb: Add swiotlb bounce buffer remap function for HV IVM Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 2/5] x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has() Tianyu Lan
2021-12-07 9:47 ` Borislav Petkov
2021-12-07 11:18 ` Tianyu Lan
2021-12-08 14:52 ` [PATCH V6.1] " Tianyu Lan
2021-12-08 15:12 ` Tianyu Lan
2021-12-09 20:38 ` [PATCH V6 2/5] " Michael Kelley (LINUX)
2021-12-10 11:26 ` Tianyu Lan
2021-12-07 7:55 ` [PATCH V6 3/5] hyper-v: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
2021-12-09 20:09 ` Michael Kelley (LINUX) [this message]
2021-12-10 13:25 ` Tianyu Lan
2021-12-10 14:01 ` Tianyu Lan
2021-12-07 7:56 ` [PATCH V6 4/5] scsi: storvsc: Add Isolation VM support for storvsc driver Tianyu Lan
2021-12-09 8:00 ` Long Li
2021-12-09 11:17 ` Tianyu Lan
2021-12-07 7:56 ` [PATCH V6 5/5] net: netvsc: Add Isolation VM support for netvsc driver Tianyu Lan
2021-12-08 20:14 ` Haiyang Zhang
2021-12-09 8:08 ` Tianyu Lan
2021-12-09 19:54 ` Michael Kelley (LINUX)
2021-12-09 20:40 ` Haiyang Zhang
-- strict thread matches above, loose matches on Subject: below --
2021-12-07 7:19 [PATCH V6 0/5] x86/Hyper-V: Add Hyper-V Isolation VM support(Second part) Tianyu Lan
2021-12-07 7:19 ` [PATCH V6 3/5] hyper-v: Enable swiotlb bounce buffer for Isolation VM Tianyu Lan
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