Re: [PATCH v3 3/3] pci: ROM preallocation for incoming migration
On Mon, May 22, 2023 at 11:44:32AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> On 19.05.23 08:34, Michael S. Tsirkin wrote:
> > On Mon, May 15, 2023 at 03:52:29PM +0300, Vladimir Sementsov-Ogievskiy
> > wrote:
> > > On incoming migration we have the following sequence to load option
> > > ROM:
> > >
> > > 1. On device realize we do normal load ROM from the file
> > >
> > > 2. Than, on incoming migration we rewrite ROM from the incoming RAM
> > > block. If sizes mismatch we fail, like this:
> > >
> > > Size mismatch: :00:03.0/virtio-net-pci.rom: 0x4 != 0x8:
> > > Invalid argument
> > >
> > > This is not ideal when we migrate to updated distribution: we have to
> > > keep old ROM files in new distribution and be careful around romfile
> > > property to load correct ROM file. Which is loaded actually just to
> > > allocate the ROM with correct length.
> > >
> > > Note, that romsize property doesn't really help: if we try to specify
> > > it when default romfile is larger, it fails with something like:
> > >
> > > romfile "efi-virtio.rom" (160768 bytes) is too large for ROM size
> > > 65536
> > >
> > > Let's just ignore ROM file when romsize is specified and we are in
> > > incoming migration state. In other words, we need only to preallocate
> > > ROM of specified size, local ROM file is unrelated.
> > >
> > > This way:
> > >
> > > If romsize was specified on source, we just use same commandline as on
> > > source, and migration will work independently of local ROM files on
> > > target.
> > >
> > > If romsize was not specified on source (and we have mismatching local
> > > ROM file on target host), we have to specify romsize on target to match
> > > source romsize. romfile parameter may be kept same as on source or may
> > > be dropped, the file is not loaded anyway.
> > >
> > > As a bonus we avoid extra reading from ROM file on target.
> > >
> > > Note: when we don't have romsize parameter on source command line and
> > > need it for target, it may be calculated as aligned up to power of two
> > > size of ROM file on source (if we know, which file is it) or,
> > > alternatively it may be retrieved from source QEMU by QMP qom-get
> > > command, like
> > >
> > >{ "execute": "qom-get",
> > > "arguments": {
> > >"path": "/machine/peripheral/CARD_ID/virtio-net-pci.rom[0]",
> > >"property": "size" } }
> > >
> > > Suggested-by: Michael S. Tsirkin
> > > Signed-off-by: Vladimir Sementsov-Ogievskiy
> > > Reviewed-by: David Hildenbrand
> > > Reviewed-by: Juan Quintela
> >
> >
> > Breaks build here:
> >
> > In function ‘pci_add_option_rom’,
> > inlined from ‘pci_qdev_realize’ at ../hw/pci/pci.c:2155:5:
> > ../hw/pci/pci.c:2395:13: error: ‘size’ may be used uninitialized
> > [-Werror=maybe-uninitialized]
> > 2395 | if (load_image_size(path, ptr, size) < 0) {
> >| ^~~~
> > ../hw/pci/pci.c: In function ‘pci_qdev_realize’:
> > ../hw/pci/pci.c:2312:13: note: ‘size’ was declared here
> > 2312 | int64_t size;
> >| ^~~~
> >
> >
>
> Hmm, but works for me. Anyway that's obviously false-positive, if we are
> here, size is initialized in previous block if (load_file || ..).
>
> So, may be add simply this:
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 0f0c83c02f..075c998284 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -2307,7 +2307,7 @@ static void pci_patch_ids(PCIDevice *pdev, uint8_t
> *ptr, uint32_t size)
> static void pci_add_option_rom(PCIDevice *pdev, bool is_default_rom,
> Error **errp)
> {
> -int64_t size;
> +int64_t size = 0; /* fix "uninitialized" false-positive */
I'd even drop the comment, we will not remember to remove it.
just mention in commit log.
OK, pls repost with this fix. Minor so include acks posted so far. Thanks!
> g_autofree char *path = NULL;
> char name[32];
> const VMStateDescription *vmsd;
>
>
> >
> > > ---
> > > hw/pci/pci.c | 77 ++--
> > > 1 file changed, 45 insertions(+), 32 deletions(-)
> > >
> > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > > index 3a0107758c..0f0c83c02f 100644
> > > --- a/hw/pci/pci.c
> > > +++ b/hw/pci/pci.c
> > > @@ -36,6 +36,7 @@
> > > #include "migration/vmstate.h"
> > > #include "net/net.h"
> > > #include "sysemu/numa.h"
> > > +#include "sysemu/runstate.h"
> > > #include "sysemu/sysemu.h"
> > > #include "hw/loader.h"
> > > #include "qemu/error-report.h"
> > > @@ -2308,10 +2309,16 @@ static void pci_add_option_rom(PCIDevice *pdev,
> > > bool is_default_rom,
> > > {
> > > int64_t size;
> > > g_autofree char *path = NULL;
> > > -void *ptr;
> > > char name[32];
> > > const VMStateDescription *vmsd;
> > > +/*
> > > + * In case of incoming migration ROM will come with migration
> > > stream, no
> > > + * reason to load the
Re: [PATCH v3 3/3] pci: ROM preallocation for incoming migration
On 19.05.23 08:34, Michael S. Tsirkin wrote:
On Mon, May 15, 2023 at 03:52:29PM +0300, Vladimir Sementsov-Ogievskiy wrote:
On incoming migration we have the following sequence to load option
ROM:
1. On device realize we do normal load ROM from the file
2. Than, on incoming migration we rewrite ROM from the incoming RAM
block. If sizes mismatch we fail, like this:
Size mismatch: :00:03.0/virtio-net-pci.rom: 0x4 != 0x8:
Invalid argument
This is not ideal when we migrate to updated distribution: we have to
keep old ROM files in new distribution and be careful around romfile
property to load correct ROM file. Which is loaded actually just to
allocate the ROM with correct length.
Note, that romsize property doesn't really help: if we try to specify
it when default romfile is larger, it fails with something like:
romfile "efi-virtio.rom" (160768 bytes) is too large for ROM size 65536
Let's just ignore ROM file when romsize is specified and we are in
incoming migration state. In other words, we need only to preallocate
ROM of specified size, local ROM file is unrelated.
This way:
If romsize was specified on source, we just use same commandline as on
source, and migration will work independently of local ROM files on
target.
If romsize was not specified on source (and we have mismatching local
ROM file on target host), we have to specify romsize on target to match
source romsize. romfile parameter may be kept same as on source or may
be dropped, the file is not loaded anyway.
As a bonus we avoid extra reading from ROM file on target.
Note: when we don't have romsize parameter on source command line and
need it for target, it may be calculated as aligned up to power of two
size of ROM file on source (if we know, which file is it) or,
alternatively it may be retrieved from source QEMU by QMP qom-get
command, like
{ "execute": "qom-get",
"arguments": {
"path": "/machine/peripheral/CARD_ID/virtio-net-pci.rom[0]",
"property": "size" } }
Suggested-by: Michael S. Tsirkin
Signed-off-by: Vladimir Sementsov-Ogievskiy
Reviewed-by: David Hildenbrand
Reviewed-by: Juan Quintela
Breaks build here:
In function ‘pci_add_option_rom’,
inlined from ‘pci_qdev_realize’ at ../hw/pci/pci.c:2155:5:
../hw/pci/pci.c:2395:13: error: ‘size’ may be used uninitialized
[-Werror=maybe-uninitialized]
2395 | if (load_image_size(path, ptr, size) < 0) {
| ^~~~
../hw/pci/pci.c: In function ‘pci_qdev_realize’:
../hw/pci/pci.c:2312:13: note: ‘size’ was declared here
2312 | int64_t size;
| ^~~~
Hmm, but works for me. Anyway that's obviously false-positive, if we are here,
size is initialized in previous block if (load_file || ..).
So, may be add simply this:
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 0f0c83c02f..075c998284 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2307,7 +2307,7 @@ static void pci_patch_ids(PCIDevice *pdev, uint8_t *ptr,
uint32_t size)
static void pci_add_option_rom(PCIDevice *pdev, bool is_default_rom,
Error **errp)
{
-int64_t size;
+int64_t size = 0; /* fix "uninitialized" false-positive */
g_autofree char *path = NULL;
char name[32];
const VMStateDescription *vmsd;
---
hw/pci/pci.c | 77 ++--
1 file changed, 45 insertions(+), 32 deletions(-)
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 3a0107758c..0f0c83c02f 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -36,6 +36,7 @@
#include "migration/vmstate.h"
#include "net/net.h"
#include "sysemu/numa.h"
+#include "sysemu/runstate.h"
#include "sysemu/sysemu.h"
#include "hw/loader.h"
#include "qemu/error-report.h"
@@ -2308,10 +2309,16 @@ static void pci_add_option_rom(PCIDevice *pdev, bool
is_default_rom,
{
int64_t size;
g_autofree char *path = NULL;
-void *ptr;
char name[32];
const VMStateDescription *vmsd;
+/*
+ * In case of incoming migration ROM will come with migration stream, no
+ * reason to load the file. Neither we want to fail if local ROM file
+ * mismatches with specified romsize.
+ */
+bool load_file = !runstate_check(RUN_STATE_INMIGRATE);
+
if (!pdev->romfile || !strlen(pdev->romfile)) {
return;
}
@@ -2341,32 +2348,35 @@ static void pci_add_option_rom(PCIDevice *pdev, bool
is_default_rom,
return;
}
-path = qemu_find_file(QEMU_FILE_TYPE_BIOS, pdev->romfile);
-if (path == NULL) {
-path = g_strdup(pdev->romfile);
-}
+if (load_file || pdev->romsize == -1) {
+path = qemu_find_file(QEMU_FILE_TYPE_BIOS, pdev->romfile);
+if (path == NULL) {
+path = g_strdup(pdev->romfile);
+}
-size = get_image_size(path);
-if (size < 0) {
-error_setg(errp, "failed to find romfile \"%s\"", pdev->romfile);
-return;
Re: [PATCH v3 3/3] pci: ROM preallocation for incoming migration
On Mon, May 15, 2023 at 03:52:29PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> On incoming migration we have the following sequence to load option
> ROM:
>
> 1. On device realize we do normal load ROM from the file
>
> 2. Than, on incoming migration we rewrite ROM from the incoming RAM
>block. If sizes mismatch we fail, like this:
>
> Size mismatch: :00:03.0/virtio-net-pci.rom: 0x4 != 0x8:
> Invalid argument
>
> This is not ideal when we migrate to updated distribution: we have to
> keep old ROM files in new distribution and be careful around romfile
> property to load correct ROM file. Which is loaded actually just to
> allocate the ROM with correct length.
>
> Note, that romsize property doesn't really help: if we try to specify
> it when default romfile is larger, it fails with something like:
>
> romfile "efi-virtio.rom" (160768 bytes) is too large for ROM size 65536
>
> Let's just ignore ROM file when romsize is specified and we are in
> incoming migration state. In other words, we need only to preallocate
> ROM of specified size, local ROM file is unrelated.
>
> This way:
>
> If romsize was specified on source, we just use same commandline as on
> source, and migration will work independently of local ROM files on
> target.
>
> If romsize was not specified on source (and we have mismatching local
> ROM file on target host), we have to specify romsize on target to match
> source romsize. romfile parameter may be kept same as on source or may
> be dropped, the file is not loaded anyway.
>
> As a bonus we avoid extra reading from ROM file on target.
>
> Note: when we don't have romsize parameter on source command line and
> need it for target, it may be calculated as aligned up to power of two
> size of ROM file on source (if we know, which file is it) or,
> alternatively it may be retrieved from source QEMU by QMP qom-get
> command, like
>
> { "execute": "qom-get",
> "arguments": {
> "path": "/machine/peripheral/CARD_ID/virtio-net-pci.rom[0]",
> "property": "size" } }
>
> Suggested-by: Michael S. Tsirkin
> Signed-off-by: Vladimir Sementsov-Ogievskiy
> Reviewed-by: David Hildenbrand
> Reviewed-by: Juan Quintela
Breaks build here:
In function ‘pci_add_option_rom’,
inlined from ‘pci_qdev_realize’ at ../hw/pci/pci.c:2155:5:
../hw/pci/pci.c:2395:13: error: ‘size’ may be used uninitialized
[-Werror=maybe-uninitialized]
2395 | if (load_image_size(path, ptr, size) < 0) {
| ^~~~
../hw/pci/pci.c: In function ‘pci_qdev_realize’:
../hw/pci/pci.c:2312:13: note: ‘size’ was declared here
2312 | int64_t size;
| ^~~~
> ---
> hw/pci/pci.c | 77 ++--
> 1 file changed, 45 insertions(+), 32 deletions(-)
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 3a0107758c..0f0c83c02f 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -36,6 +36,7 @@
> #include "migration/vmstate.h"
> #include "net/net.h"
> #include "sysemu/numa.h"
> +#include "sysemu/runstate.h"
> #include "sysemu/sysemu.h"
> #include "hw/loader.h"
> #include "qemu/error-report.h"
> @@ -2308,10 +2309,16 @@ static void pci_add_option_rom(PCIDevice *pdev, bool
> is_default_rom,
> {
> int64_t size;
> g_autofree char *path = NULL;
> -void *ptr;
> char name[32];
> const VMStateDescription *vmsd;
>
> +/*
> + * In case of incoming migration ROM will come with migration stream, no
> + * reason to load the file. Neither we want to fail if local ROM file
> + * mismatches with specified romsize.
> + */
> +bool load_file = !runstate_check(RUN_STATE_INMIGRATE);
> +
> if (!pdev->romfile || !strlen(pdev->romfile)) {
> return;
> }
> @@ -2341,32 +2348,35 @@ static void pci_add_option_rom(PCIDevice *pdev, bool
> is_default_rom,
> return;
> }
>
> -path = qemu_find_file(QEMU_FILE_TYPE_BIOS, pdev->romfile);
> -if (path == NULL) {
> -path = g_strdup(pdev->romfile);
> -}
> +if (load_file || pdev->romsize == -1) {
> +path = qemu_find_file(QEMU_FILE_TYPE_BIOS, pdev->romfile);
> +if (path == NULL) {
> +path = g_strdup(pdev->romfile);
> +}
>
> -size = get_image_size(path);
> -if (size < 0) {
> -error_setg(errp, "failed to find romfile \"%s\"", pdev->romfile);
> -return;
> -} else if (size == 0) {
> -error_setg(errp, "romfile \"%s\" is empty", pdev->romfile);
> -return;
> -} else if (size > 2 * GiB) {
> -error_setg(errp, "romfile \"%s\" too large (size cannot exceed 2
> GiB)",
> - pdev->romfile);
> -return;
> -}
> -if (pdev->romsize != -1) {
> -if (size > pdev->romsize) {
> -error_setg(errp, "romfile \"%s\" (%u bytes) "
> - "is too large for ROM size %u",
> - pdev->romfile, (uint32_t)
