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Re: [Qemu-devel] [PATCH] memory: fetch pmem size in get_file_size()
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH] memory: fetch pmem size in get_file_size() |
Date: |
Thu, 12 Sep 2019 12:25:51 +0200 |
User-agent: |
Mutt/1.12.1 (2019-06-15) |
On Fri, Aug 30, 2019 at 03:44:45PM -0300, Eduardo Habkost wrote:
> On Fri, Aug 30, 2019 at 10:30:56AM +0100, Stefan Hajnoczi wrote:
> > Neither stat(2) nor lseek(2) report the size of Linux devdax pmem
> > character device nodes. Commit 314aec4a6e06844937f1677f6cba21981005f389
> > ("hostmem-file: reject invalid pmem file sizes") added code to
> > hostmem-file.c to fetch the size from sysfs and compare against the
> > user-provided size=NUM parameter:
> >
> > if (backend->size > size) {
> > error_setg(errp, "size property %" PRIu64 " is larger than "
> > "pmem file \"%s\" size %" PRIu64, backend->size,
> > fb->mem_path, size);
> > return;
> > }
> >
> > It turns out that exec.c:qemu_ram_alloc_from_fd() already has an
> > equivalent size check but it skips devdax pmem character devices because
> > lseek(2) returns 0:
> >
> > if (file_size > 0 && file_size < size) {
> > error_setg(errp, "backing store %s size 0x%" PRIx64
> > " does not match 'size' option 0x" RAM_ADDR_FMT,
> > mem_path, file_size, size);
> > return NULL;
> > }
> >
> > This patch moves the devdax pmem file size code into get_file_size() so
> > that we check the memory size in a single place:
> > qemu_ram_alloc_from_fd(). This simplifies the code and makes it more
> > general.
> >
> > This also fixes the problem that hostmem-file only checks the devdax
> > pmem file size when the pmem=on parameter is given. An unchecked
> > size=NUM parameter can lead to SIGBUS in QEMU so we must always fetch
> > the file size for Linux devdax pmem character device nodes.
> >
> > Signed-off-by: Stefan Hajnoczi <address@hidden>
>
> Reviewed-by: Eduardo Habkost <address@hidden>
>
> Paolo, do you want to queue this, or should it go through my
> memory backend queue?
Ping for Paolo
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- Re: [Qemu-devel] [PATCH] memory: fetch pmem size in get_file_size(),
Stefan Hajnoczi <=