[PATCH v2 04/12] Drivers: hv: Explicitly request decrypted in vmap_pfn() calls

Michael Kelley
2022-11-11T06:22:34Z

In preparation for a subsequent patch, 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 a subsequent patch
that will cause vmap_pfn() to mask the PFNs to being below the
shared_gpa_boundary. While another subsesquent patch removes the
vmap_pfn() calls entirely, this temporary tweak avoids the need
for a large patch that makes all the changes at once.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
arch/x86/hyperv/ivm.c | 2 +-
drivers/hv/ring_buffer.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index f33c67e..e8be4c2 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -343,7 +343,7 @@ void *hv_map_memory(void *addr, unsigned long size)
pfns[i] = vmalloc_to_pfn(addr + i * PAGE_SIZE) +
(ms_hyperv.shared_gpa_boundary >> PAGE_SHIFT);

- vaddr = vmap_pfn(pfns, size / PAGE_SIZE, PAGE_KERNEL_IO);
+ vaddr = vmap_pfn(pfns, size / PAGE_SIZE, pgprot_decrypted(PAGE_KERNEL_NOENC));
kfree(pfns);

return vaddr;
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 59a4aa8..b4a91b1 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_NOENC));
kfree(pfns_wraparound);

if (!ring_info->ring_buffer)
--
1.8.3.1