This is a note to let you know that I've just added the patch titled
riscv: Fix IPIs usage in kfence_protect_page()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-fix-ipis-usage-in-kfence_protect_page.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 89e3d877fe251e0610c885b362c0db27494ad3b8
Author: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Date: Mon Dec 9 08:41:25 2024 +0100
riscv: Fix IPIs usage in kfence_protect_page()
[ Upstream commit b3431a8bb336cece8adc452437befa7d4534b2fd ]
flush_tlb_kernel_range() may use IPIs to flush the TLBs of all the
cores, which triggers the following warning when the irqs are disabled:
[ 3.455330] WARNING: CPU: 1 PID: 0 at kernel/smp.c:815 smp_call_function_many_cond+0x452/0x520
[ 3.456647] Modules linked in:
[ 3.457218] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.12.0-rc7-00010-g91d3de7240b8 #1
[ 3.457416] Hardware name: QEMU QEMU Virtual Machine, BIOS
[ 3.457633] epc : smp_call_function_many_cond+0x452/0x520
[ 3.457736] ra : on_each_cpu_cond_mask+0x1e/0x30
[ 3.457786] epc : ffffffff800b669a ra : ffffffff800b67c2 sp : ff2000000000bb50
[ 3.457824] gp : ffffffff815212b8 tp : ff6000008014f080 t0 : 000000000000003f
[ 3.457859] t1 : ffffffff815221e0 t2 : 000000000000000f s0 : ff2000000000bc10
[ 3.457920] s1 : 0000000000000040 a0 : ffffffff815221e0 a1 : 0000000000000001
[ 3.457953] a2 : 0000000000010000 a3 : 0000000000000003 a4 : 0000000000000000
[ 3.458006] a5 : 0000000000000000 a6 : ffffffffffffffff a7 : 0000000000000000
[ 3.458042] s2 : ffffffff815223be s3 : 00fffffffffff000 s4 : ff600001ffe38fc0
[ 3.458076] s5 : ff600001ff950d00 s6 : 0000000200000120 s7 : 0000000000000001
[ 3.458109] s8 : 0000000000000001 s9 : ff60000080841ef0 s10: 0000000000000001
[ 3.458141] s11: ffffffff81524812 t3 : 0000000000000001 t4 : ff60000080092bc0
[ 3.458172] t5 : 0000000000000000 t6 : ff200000000236d0
[ 3.458203] status: 0000000200000100 badaddr: ffffffff800b669a cause: 0000000000000003
[ 3.458373] [<ffffffff800b669a>] smp_call_function_many_cond+0x452/0x520
[ 3.458593] [<ffffffff800b67c2>] on_each_cpu_cond_mask+0x1e/0x30
[ 3.458625] [<ffffffff8000e4ca>] __flush_tlb_range+0x118/0x1ca
[ 3.458656] [<ffffffff8000e6b2>] flush_tlb_kernel_range+0x1e/0x26
[ 3.458683] [<ffffffff801ea56a>] kfence_protect+0xc0/0xce
[ 3.458717] [<ffffffff801e9456>] kfence_guarded_free+0xc6/0x1c0
[ 3.458742] [<ffffffff801e9d6c>] __kfence_free+0x62/0xc6
[ 3.458764] [<ffffffff801c57d8>] kfree+0x106/0x32c
[ 3.458786] [<ffffffff80588cf2>] detach_buf_split+0x188/0x1a8
[ 3.458816] [<ffffffff8058708c>] virtqueue_get_buf_ctx+0xb6/0x1f6
[ 3.458839] [<ffffffff805871da>] virtqueue_get_buf+0xe/0x16
[ 3.458880] [<ffffffff80613d6a>] virtblk_done+0x5c/0xe2
[ 3.458908] [<ffffffff8058766e>] vring_interrupt+0x6a/0x74
[ 3.458930] [<ffffffff800747d8>] __handle_irq_event_percpu+0x7c/0xe2
[ 3.458956] [<ffffffff800748f0>] handle_irq_event+0x3c/0x86
[ 3.458978] [<ffffffff800786cc>] handle_simple_irq+0x9e/0xbe
[ 3.459004] [<ffffffff80073934>] generic_handle_domain_irq+0x1c/0x2a
[ 3.459027] [<ffffffff804bf87c>] imsic_handle_irq+0xba/0x120
[ 3.459056] [<ffffffff80073934>] generic_handle_domain_irq+0x1c/0x2a
[ 3.459080] [<ffffffff804bdb76>] riscv_intc_aia_irq+0x24/0x34
[ 3.459103] [<ffffffff809d0452>] handle_riscv_irq+0x2e/0x4c
[ 3.459133] [<ffffffff809d923e>] call_on_irq_stack+0x32/0x40
So only flush the local TLB and let the lazy kfence page fault handling
deal with the faults which could happen when a core has an old protected
pte version cached in its TLB. That leads to potential inaccuracies which
can be tolerated when using kfence.
Fixes: 47513f243b45 ("riscv: Enable KFENCE for riscv64")
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20241209074125.52322-1-alexghiti@xxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/include/asm/kfence.h b/arch/riscv/include/asm/kfence.h
index d887a54042aa..5d013dc52c0b 100644
--- a/arch/riscv/include/asm/kfence.h
+++ b/arch/riscv/include/asm/kfence.h
@@ -55,7 +55,9 @@ static inline bool kfence_protect_page(unsigned long addr, bool protect)
else
set_pte(pte, __pte(pte_val(*pte) | _PAGE_PRESENT));
- flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ preempt_disable();
+ local_flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ preempt_enable();
return true;
}
