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Revision c15e0ae42c8e5a61e9aca8aac920517cf7b3e94e authored by Li RongQing on 09 March 2022, 08:35:44 UTC, committed by Paolo Bonzini on 02 April 2022, 09:37:27 UTC 
KVM: x86: fix sending PV IPI
 
If apic_id is less than min, and (max - apic_id) is greater than
KVM_IPI_CLUSTER_SIZE, then the third check condition is satisfied but
the new apic_id does not fit the bitmask.  In this case __send_ipi_mask
should send the IPI.

This is mostly theoretical, but it can happen if the apic_ids on three
iterations of the loop are for example 1, KVM_IPI_CLUSTER_SIZE, 0.

Fixes: aaffcfd1e82 ("KVM: X86: Implement PV IPIs in linux guest")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1646814944-51801-1-git-send-email-lirongqing@baidu.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 2a8859f
Raw File
io-mapping.c 
// SPDX-License-Identifier: GPL-2.0-only

#include <linux/mm.h>
#include <linux/io-mapping.h>

/**
 * io_mapping_map_user - remap an I/O mapping to userspace
 * @iomap: the source io_mapping
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
int io_mapping_map_user(struct io_mapping *iomap, struct vm_area_struct *vma,
		unsigned long addr, unsigned long pfn, unsigned long size)
{
	vm_flags_t expected_flags = VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;

	if (WARN_ON_ONCE((vma->vm_flags & expected_flags) != expected_flags))
		return -EINVAL;

	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
	return remap_pfn_range_notrack(vma, addr, pfn, size,
		__pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
			 (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK)));
}
EXPORT_SYMBOL_GPL(io_mapping_map_user);
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