From d33ddc92db8a61416473ff3d7f1c621c50733dc0 Mon Sep 17 00:00:00 2001 From: Michael Kelley Date: Sun, 26 Mar 2023 06:51:58 -0700 Subject: Drivers: hv: Explicitly request decrypted in vmap_pfn() calls Update vmap_pfn() calls to explicitly request that the mapping be for decrypted access to the memory. There's no change in functionality since the PFNs passed to vmap_pfn() are above the shared_gpa_boundary, implicitly producing a decrypted mapping. But explicitly requesting "decrypted" allows the code to work before and after changes that cause vmap_pfn() to mask the PFNs to being below the shared_gpa_boundary. Signed-off-by: Michael Kelley Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tianyu Lan Link: https://lore.kernel.org/r/1679838727-87310-4-git-send-email-mikelley@microsoft.com --- drivers/hv/ring_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/hv') diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index c6692fd5ab15..2111e97c3b63 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -211,7 +211,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, ring_info->ring_buffer = (struct hv_ring_buffer *) vmap_pfn(pfns_wraparound, page_cnt * 2 - 1, - PAGE_KERNEL); + pgprot_decrypted(PAGE_KERNEL)); kfree(pfns_wraparound); if (!ring_info->ring_buffer) -- cgit From 812b0597fb4043240724e4c7bed7ba1fe15c0e3f Mon Sep 17 00:00:00 2001 From: Michael Kelley Date: Sun, 26 Mar 2023 06:52:01 -0700 Subject: x86/hyperv: Change vTOM handling to use standard coco mechanisms Hyper-V guests on AMD SEV-SNP hardware have the option of using the "virtual Top Of Memory" (vTOM) feature specified by the SEV-SNP architecture. With vTOM, shared vs. private memory accesses are controlled by splitting the guest physical address space into two halves. vTOM is the dividing line where the uppermost bit of the physical address space is set; e.g., with 47 bits of guest physical address space, vTOM is 0x400000000000 (bit 46 is set). Guest physical memory is accessible at two parallel physical addresses -- one below vTOM and one above vTOM. Accesses below vTOM are private (encrypted) while accesses above vTOM are shared (decrypted). In this sense, vTOM is like the GPA.SHARED bit in Intel TDX. Support for Hyper-V guests using vTOM was added to the Linux kernel in two patch sets[1][2]. This support treats the vTOM bit as part of the physical address. For accessing shared (decrypted) memory, these patch sets create a second kernel virtual mapping that maps to physical addresses above vTOM. A better approach is to treat the vTOM bit as a protection flag, not as part of the physical address. This new approach is like the approach for the GPA.SHARED bit in Intel TDX. Rather than creating a second kernel virtual mapping, the existing mapping is updated using recently added coco mechanisms. When memory is changed between private and shared using set_memory_decrypted() and set_memory_encrypted(), the PTEs for the existing kernel mapping are changed to add or remove the vTOM bit in the guest physical address, just as with TDX. The hypercalls to change the memory status on the host side are made using the existing callback mechanism. Everything just works, with a minor tweak to map the IO-APIC to use private accesses. To accomplish the switch in approach, the following must be done: * Update Hyper-V initialization to set the cc_mask based on vTOM and do other coco initialization. * Update physical_mask so the vTOM bit is no longer treated as part of the physical address * Remove CC_VENDOR_HYPERV and merge the associated vTOM functionality under CC_VENDOR_AMD. Update cc_mkenc() and cc_mkdec() to set/clear the vTOM bit as a protection flag. * Code already exists to make hypercalls to inform Hyper-V about pages changing between shared and private. Update this code to run as a callback from __set_memory_enc_pgtable(). * Remove the Hyper-V special case from __set_memory_enc_dec() * Remove the Hyper-V specific call to swiotlb_update_mem_attributes() since mem_encrypt_init() will now do it. * Add a Hyper-V specific implementation of the is_private_mmio() callback that returns true for the IO-APIC and vTPM MMIO addresses [1] https://lore.kernel.org/all/20211025122116.264793-1-ltykernel@gmail.com/ [2] https://lore.kernel.org/all/20211213071407.314309-1-ltykernel@gmail.com/ [ bp: Touchups. ] Signed-off-by: Michael Kelley Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/1679838727-87310-7-git-send-email-mikelley@microsoft.com --- drivers/hv/vmbus_drv.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/hv') diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index d24dd65b33d4..e9e1c4139e0d 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -2156,7 +2156,6 @@ void vmbus_device_unregister(struct hv_device *device_obj) * VMBUS is an acpi enumerated device. Get the information we * need from DSDT. */ -#define VTPM_BASE_ADDRESS 0xfed40000 static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx) { resource_size_t start = 0; -- cgit