Re: [PATCH v3 5/7] mshv: detect and report SEV-SNP support at init
From: sashiko-bot@kernel.org
Date: 2026-08-25 04:19:47
Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] Missing memory barriers when updating and reading `mshv_ready` allows concurrent userspace opens to access uninitialized driver state on weakly-ordered architectures. --
--- Patch [5]: [PATCH v3 5/7] mshv: detect and report SEV-SNP support at init ---commit fb8f9421bc97a7ed49258a973cb3c9b05f5b3049 Author: Wei Liu [off-list ref] mshv: detect and report SEV-SNP support at init This commit queries MSHV dynamic processor features during parent initialization to report SEV-SNP availability and the maximum number of encrypted partitions. It also introduces a readiness flag to reject userspace opens until initialization is complete.
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diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c --- a/drivers/hv/mshv_root_main.c +++ b/drivers/hv/mshv_root_main.c
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@@ -2757,7 +2759,7 @@ static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl, static int mshv_dev_open(struct inode *inode, struct file *filp) { - return 0; + return READ_ONCE(mshv_ready) ? 0 : -EAGAIN;
[Severity: High] Since READ_ONCE() does not provide a load-acquire barrier, could subsequent loads in the ioctl path be reordered on weakly-ordered architectures like ARM64? If a userspace process concurrently opens the device and calls an ioctl while the module is initializing, it might observe mshv_ready as true but still access uninitialized driver structures. Would using smp_load_acquire() here prevent this reordering? [ ... ]
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@@ -3022,6 +3124,7 @@ static int __init mshv_parent_partition_init(void) hash_init(mshv_root.pt_htable); hv_setup_mshv_handler(mshv_isr); + WRITE_ONCE(mshv_ready, true);
[Severity: High] Because WRITE_ONCE() lacks a store-release barrier, is it possible for the CPU to commit this store before the preceding stores that initialize the driver state, such as the workqueue allocation or mshv_root.pt_htable? Using smp_store_release() instead would ensure all preceding initialization is globally visible before userspace can successfully open the device. -- Sashiko AI review · https://sashiko.dev/#/patchset/20260825040505.826600-1-weh@linux.microsoft.com?part=5