| Message ID | 1331049010-24312-1-git-send-email-avi@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 2012-03-06 16:50, Avi Kivity wrote: > The kvmvapic code remaps a section of ROM as RAM to allow the guest to > maintain state there. It is careful to align the section size to a page > boundary, to avoid creating subpages, but neglects to do the same for > the start address. These leads to an assert later on when the memory > core tries to create a page which is half RAM and half ROM. > > Fix by aligning the start address to a page boundary. > > This can be triggered by running qemu-system-x86_64 -enable-kvm -vga none. > > Signed-off-by: Avi Kivity <avi@redhat.com> > --- > hw/kvmvapic.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/hw/kvmvapic.c b/hw/kvmvapic.c > index 36ccfbc..e8bfeec 100644 > --- a/hw/kvmvapic.c > +++ b/hw/kvmvapic.c > @@ -578,8 +578,10 @@ static void vapic_map_rom_writable(VAPICROMState *s) > rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE; > s->rom_size = rom_size; > > - /* We need to round up to avoid creating subpages > + /* We need to round to avoid creating subpages > * from which we cannot run code. */ > + rom_size += rom_paddr & ~TARGET_PAGE_MASK; > + rom_paddr &= TARGET_PAGE_MASK; > rom_size = TARGET_PAGE_ALIGN(rom_size); > > memory_region_init_alias(&s->rom, "kvmvapic-rom", section.mr, rom_paddr, Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
On 03/06/2012 09:50 AM, Avi Kivity wrote: > The kvmvapic code remaps a section of ROM as RAM to allow the guest to > maintain state there. It is careful to align the section size to a page > boundary, to avoid creating subpages, but neglects to do the same for > the start address. These leads to an assert later on when the memory > core tries to create a page which is half RAM and half ROM. > > Fix by aligning the start address to a page boundary. > > This can be triggered by running qemu-system-x86_64 -enable-kvm -vga none. > > Signed-off-by: Avi Kivity<avi@redhat.com> Tested-by: Anthony Liguori <aliguori@us.ibm.com> Are you going to do a PULL request or do you want me to apply directly? Regards, Anthony Liguori > --- > hw/kvmvapic.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/hw/kvmvapic.c b/hw/kvmvapic.c > index 36ccfbc..e8bfeec 100644 > --- a/hw/kvmvapic.c > +++ b/hw/kvmvapic.c > @@ -578,8 +578,10 @@ static void vapic_map_rom_writable(VAPICROMState *s) > rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE; > s->rom_size = rom_size; > > - /* We need to round up to avoid creating subpages > + /* We need to round to avoid creating subpages > * from which we cannot run code. */ > + rom_size += rom_paddr& ~TARGET_PAGE_MASK; > + rom_paddr&= TARGET_PAGE_MASK; > rom_size = TARGET_PAGE_ALIGN(rom_size); > > memory_region_init_alias(&s->rom, "kvmvapic-rom", section.mr, rom_paddr,
On 03/06/2012 09:50 AM, Avi Kivity wrote: > The kvmvapic code remaps a section of ROM as RAM to allow the guest to > maintain state there. It is careful to align the section size to a page > boundary, to avoid creating subpages, but neglects to do the same for > the start address. These leads to an assert later on when the memory > core tries to create a page which is half RAM and half ROM. > > Fix by aligning the start address to a page boundary. > > This can be triggered by running qemu-system-x86_64 -enable-kvm -vga none. > > Signed-off-by: Avi Kivity<avi@redhat.com> Applied. Thanks. Regards, Anthony Liguori > --- > hw/kvmvapic.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/hw/kvmvapic.c b/hw/kvmvapic.c > index 36ccfbc..e8bfeec 100644 > --- a/hw/kvmvapic.c > +++ b/hw/kvmvapic.c > @@ -578,8 +578,10 @@ static void vapic_map_rom_writable(VAPICROMState *s) > rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE; > s->rom_size = rom_size; > > - /* We need to round up to avoid creating subpages > + /* We need to round to avoid creating subpages > * from which we cannot run code. */ > + rom_size += rom_paddr& ~TARGET_PAGE_MASK; > + rom_paddr&= TARGET_PAGE_MASK; > rom_size = TARGET_PAGE_ALIGN(rom_size); > > memory_region_init_alias(&s->rom, "kvmvapic-rom", section.mr, rom_paddr,
On 03/14/2012 10:33 PM, Anthony Liguori wrote: > On 03/06/2012 09:50 AM, Avi Kivity wrote: >> The kvmvapic code remaps a section of ROM as RAM to allow the guest to >> maintain state there. It is careful to align the section size to a page >> boundary, to avoid creating subpages, but neglects to do the same for >> the start address. These leads to an assert later on when the memory >> core tries to create a page which is half RAM and half ROM. >> >> Fix by aligning the start address to a page boundary. >> >> This can be triggered by running qemu-system-x86_64 -enable-kvm -vga >> none. >> >> Signed-off-by: Avi Kivity<avi@redhat.com> > > Tested-by: Anthony Liguori <aliguori@us.ibm.com> > > Are you going to do a PULL request or do you want me to apply directly? I forgot all about it, sorry.
On 03/15/2012 04:55 AM, Avi Kivity wrote: > On 03/14/2012 10:33 PM, Anthony Liguori wrote: >> On 03/06/2012 09:50 AM, Avi Kivity wrote: >>> The kvmvapic code remaps a section of ROM as RAM to allow the guest to >>> maintain state there. It is careful to align the section size to a page >>> boundary, to avoid creating subpages, but neglects to do the same for >>> the start address. These leads to an assert later on when the memory >>> core tries to create a page which is half RAM and half ROM. >>> >>> Fix by aligning the start address to a page boundary. >>> >>> This can be triggered by running qemu-system-x86_64 -enable-kvm -vga >>> none. >>> >>> Signed-off-by: Avi Kivity<avi@redhat.com> >> >> Tested-by: Anthony Liguori<aliguori@us.ibm.com> >> >> Are you going to do a PULL request or do you want me to apply directly? > > I forgot all about it, sorry. No worries. I actually caught the bug in the original pull request but do to a bug in qemu-test, when I tried to bisect, things got weird and I mistakenly thought the real problem had been introduced earlier. Regards, Anthony Liguori >
diff --git a/hw/kvmvapic.c b/hw/kvmvapic.c index 36ccfbc..e8bfeec 100644 --- a/hw/kvmvapic.c +++ b/hw/kvmvapic.c @@ -578,8 +578,10 @@ static void vapic_map_rom_writable(VAPICROMState *s) rom_size = ram[rom_paddr + 2] * ROM_BLOCK_SIZE; s->rom_size = rom_size; - /* We need to round up to avoid creating subpages + /* We need to round to avoid creating subpages * from which we cannot run code. */ + rom_size += rom_paddr & ~TARGET_PAGE_MASK; + rom_paddr &= TARGET_PAGE_MASK; rom_size = TARGET_PAGE_ALIGN(rom_size); memory_region_init_alias(&s->rom, "kvmvapic-rom", section.mr, rom_paddr,
The kvmvapic code remaps a section of ROM as RAM to allow the guest to maintain state there. It is careful to align the section size to a page boundary, to avoid creating subpages, but neglects to do the same for the start address. These leads to an assert later on when the memory core tries to create a page which is half RAM and half ROM. Fix by aligning the start address to a page boundary. This can be triggered by running qemu-system-x86_64 -enable-kvm -vga none. Signed-off-by: Avi Kivity <avi@redhat.com> --- hw/kvmvapic.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)