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Re: [Qemu-devel] [PATCH v2 1/3] hw/s390x/ipl: Fix alignment problems of
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/3] hw/s390x/ipl: Fix alignment problems of S390IPLState members |
Date: |
Wed, 26 Sep 2018 11:42:07 +0200 |
On Wed, 26 Sep 2018 09:38:45 +0200
Thomas Huth <address@hidden> wrote:
> The IplParameterBlock and QemuIplParameters structures are declared
> with QEMU_PACKED, so the compiler assumes that the structures do not
> need to be aligned in memory. Since the are listed after a "bool"
> within the S390IPLState, the IplParameterBlock and QemuIplParameters
> are also indeed mis-aligned in memory. This causes problems on Sparc
> during migration, since we use VMSTATE_UINT16 in vmstate_iplb to access
> the devno member for example, and the corresponding migration functions
> (like qemu_get_be16s) then try to access a 16-bit value from a mis-
> aligned memory address.
> The easiest solution to fix this problem is to move the packed structures
> to the beginning of the S390IPLState. Also add some additional comments
> here to prevent that this problem will be introduced again in the future.
>
> Signed-off-by: Thomas Huth <address@hidden>
> ---
> hw/s390x/ipl.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
> index 4e87b89..b3a07a1 100644
> --- a/hw/s390x/ipl.h
> +++ b/hw/s390x/ipl.h
> @@ -132,15 +132,15 @@ typedef struct QemuIplParameters QemuIplParameters;
> struct S390IPLState {
> /*< private >*/
> DeviceState parent_obj;
> + IplParameterBlock iplb;
> + QemuIplParameters qipl;
Hm... this is not quite the beginning of the structure; what am I
missing?
> uint64_t start_addr;
> uint64_t compat_start_addr;
> uint64_t bios_start_addr;
> uint64_t compat_bios_start_addr;
> bool enforce_bios;
> - IplParameterBlock iplb;
> bool iplb_valid;
> bool netboot;
> - QemuIplParameters qipl;
> /* reset related properties don't have to be migrated or reset */
> enum s390_reset reset_type;
> int reset_cpu_index;
> @@ -157,6 +157,7 @@ struct S390IPLState {
> bool iplbext_migration;
> };
> typedef struct S390IPLState S390IPLState;
> +QEMU_BUILD_BUG_MSG(offsetof(S390IPLState, iplb) & 3, "alignment of iplb
> wrong");
>
> #define S390_IPL_TYPE_FCP 0x00
> #define S390_IPL_TYPE_CCW 0x02
[Qemu-devel] [PATCH v2 2/3] hw/s390x/css: Remove QEMU_PACKED from struct SenseId, Thomas Huth, 2018/09/26