kernel/linux.git/drivers/hv/ring_buffer.c, branch v6.19.11

Drivers: hv: Allocate encrypted buffers when requested

2025-11-15T06:18:15+00:00

Confidential VMBus is built around using buffers not shared with the host. Support allocating encrypted buffers when requested. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Fix warnings for missing export.h header inclusion

2025-07-09T23:43:52+00:00

Fix below warning in Hyper-V drivers that comes when kernel is compiled with W=1 option. Include export.h in driver files to fix it. * warning: EXPORT_SYMBOL() is used, but #include is missing Signed-off-by: Naman Jain Reviewed-by: Nuno Das Neves Reviewed-by: Saurabh Sengar Link: https://lore.kernel.org/r/20250611100459.92900-2-namjain@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250611100459.92900-2-namjain@linux.microsoft.com>

Drivers: hv: vmbus: Remove second way of mapping ring buffers

2023-04-17T19:19:04+00:00

With changes to how Hyper-V guest VMs flip memory between private (encrypted) and shared (decrypted), it's no longer necessary to have separate code paths for mapping VMBus ring buffers for for normal VMs and for Confidential VMs. As such, remove the code path that uses vmap_pfn(), and set the protection flags argument to vmap() to account for the difference between normal and Confidential VMs. Signed-off-by: Michael Kelley Reviewed-by: Tianyu Lan Link: https://lore.kernel.org/r/1679838727-87310-10-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu

Drivers: hv: Explicitly request decrypted in vmap_pfn() calls

2023-03-27T06:46:43+00:00

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

video: hyperv_fb: Avoid taking busy spinlock on panic path

2022-11-28T16:48:20+00:00

The Hyper-V framebuffer code registers a panic notifier in order to try updating its fbdev if the kernel crashed. The notifier callback is straightforward, but it calls the vmbus_sendpacket() routine eventually, and such function takes a spinlock for the ring buffer operations. Panic path runs in atomic context, with local interrupts and preemption disabled, and all secondary CPUs shutdown. That said, taking a spinlock might cause a lockup if a secondary CPU was disabled with such lock taken. Fix it here by checking if the ring buffer spinlock is busy on Hyper-V framebuffer panic notifier; if so, bail-out avoiding the potential lockup scenario. Cc: Andrea Parri (Microsoft) Cc: Dexuan Cui Cc: Haiyang Zhang Cc: "K. Y. Srinivasan" Cc: Michael Kelley Cc: Stephen Hemminger Cc: Tianyu Lan Cc: Wei Liu Tested-by: Fabio A M Martins Signed-off-by: Guilherme G. Piccoli Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220819221731.480795-10-gpiccoli@igalia.com Signed-off-by: Wei Liu

Drivers: hv: vmbus: Refactor the ring-buffer iterator functions

2022-04-28T15:01:15+00:00

With no users of hv_pkt_iter_next_raw() and no "external" users of hv_pkt_iter_first_raw(), the iterator functions can be refactored and simplified to remove some indirection/code. Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220428145107.7878-6-parri.andrea@gmail.com Signed-off-by: Wei Liu

Drivers: hv: vmbus: Introduce vmbus_sendpacket_getid()

2022-04-25T15:51:12+00:00

The function can be used to send a VMbus packet and retrieve the corresponding transaction ID. It will be used by hv_pci. No functional change. Suggested-by: Michael Kelley Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220419122325.10078-4-parri.andrea@gmail.com Signed-off-by: Wei Liu

Drivers: hv: vmbus: Prevent load re-ordering when reading ring buffer

2022-03-29T13:19:33+00:00

When reading a packet from a host-to-guest ring buffer, there is no memory barrier between reading the write index (to see if there is a packet to read) and reading the contents of the packet. The Hyper-V host uses store-release when updating the write index to ensure that writes of the packet data are completed first. On the guest side, the processor can reorder and read the packet data before the write index, and sometimes get stale packet data. Getting such stale packet data has been observed in a reproducible case in a VM on ARM64. Fix this by using virt_load_acquire() to read the write index, ensuring that reads of the packet data cannot be reordered before it. Preventing such reordering is logically correct, and with this change, getting stale data can no longer be reproduced. Signed-off-by: Michael Kelley Reviewed-by: Andrea Parri (Microsoft) Link: https://lore.kernel.org/r/1648394710-33480-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu

Drivers: hv : vmbus: Adding NULL pointer check

2021-10-28T11:40:32+00:00

This patch fixes the following Coccinelle warning: drivers/hv/ring_buffer.c:223: alloc with no test Reported-by: Zeal Robot Signed-off-by: Lv Ruyi Link: https://lore.kernel.org/r/20211028104138.14576-1-lv.ruyi@zte.com.cn Signed-off-by: Wei Liu

Drivers: hv: vmbus: Initialize VMbus ring buffer for Isolation VM

2021-10-28T11:26:36+00:00

VMbus ring buffer are shared with host and it's need to be accessed via extra address space of Isolation VM with AMD SNP support. This patch is to map the ring buffer address in extra address space via vmap_pfn(). Hyperv set memory host visibility hvcall smears data in the ring buffer and so reset the ring buffer memory to zero after mapping. Reviewed-by: Michael Kelley Signed-off-by: Tianyu Lan Link: https://lore.kernel.org/r/20211025122116.264793-10-ltykernel@gmail.com Signed-off-by: Wei Liu