[PATCH v11 2/2] s390: virtio: PV needs VIRTIO I/O device protection
If protected virtualization is active on s390, VIRTIO has only retricted
access to the guest memory.
Define CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS and export
arch_has_restricted_virtio_memory_access to advertize VIRTIO if that's
the case, preventing a host error on access attempt.
Signed-off-by: Pierre Morel
Reviewed-by: Cornelia Huck
---
arch/s390/Kconfig | 1 +
arch/s390/mm/init.c | 10 ++
2 files changed, 11 insertions(+)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index b29fcc66ec39..938246200d39 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -820,6 +820,7 @@ menu "Virtualization"
config PROTECTED_VIRTUALIZATION_GUEST
def_bool n
prompt "Protected virtualization guest support"
+ select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
help
Select this option, if you want to be able to run this
kernel as a protected virtualization KVM guest.
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 0d282081dc1f..f40b9b63d3d6 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -160,6 +160,16 @@ bool force_dma_unencrypted(struct device *dev)
return is_prot_virt_guest();
}
+#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
+
+int arch_has_restricted_virtio_memory_access(void)
+{
+ return is_prot_virt_guest();
+}
+EXPORT_SYMBOL(arch_has_restricted_virtio_memory_access);
+
+#endif
+
/* protected virtualization */
static void pv_init(void)
{
--
2.17.1
___
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v11 2/2] s390: virtio: PV needs VIRTIO I/O device protection
On Mon, 7 Sep 2020 11:39:07 +0200 Pierre Morel wrote: > If protected virtualization is active on s390, VIRTIO has only retricted > access to the guest memory. > Define CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS and export > arch_has_restricted_virtio_memory_access to advertize VIRTIO if that's > the case, preventing a host error on access attempt. The description is a little inaccurate, but I don't care hence the r-b. The function arch_has_restricted_virtio_memory_access() returning true can not prevent the host from attempting to access memory if it decides to do so. And as far as I know there was no host error on access attempt. The page gets exported, and the host will operate on the encrypted page. But in the end we do run into trouble, which is usually fatal for the guest (not the host). What we actually do here is the following. If we detect an ill configured device we fail it (device status field), because attempting to drive it is a recipe for disaster. > > Signed-off-by: Pierre Morel > Reviewed-by: Cornelia Huck Reviewed-by: Halil Pasic ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH v11 2/2] s390: virtio: PV needs VIRTIO I/O device protection
Hi Pierre, I love your patch! Perhaps something to improve: [auto build test WARNING on s390/features] [also build test WARNING on linus/master v5.9-rc4 next-20200903] [cannot apply to linux/master kvms390/next] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Pierre-Morel/s390-virtio-let-arch-validate-VIRTIO-features/20200907-174101 base: https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git features config: s390-randconfig-r006-20200908 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 5f5a0bb0872a9673bad08b38bc0b14c42263902a) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install s390 cross compiling tool for clang build # apt-get install binutils-s390x-linux-gnu # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : \ ^ include/uapi/linux/swab.h:20:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0xff00UL) << 8) |\ ^ In file included from arch/s390/mm/init.c:20: In file included from include/linux/swap.h:9: In file included from include/linux/memcontrol.h:22: In file included from include/linux/writeback.h:14: In file included from include/linux/blk-cgroup.h:23: In file included from include/linux/blkdev.h:25: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); ~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : \ ^ include/uapi/linux/swab.h:21:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0x00ffUL) >> 8) |\ ^ In file included from arch/s390/mm/init.c:20: In file included from include/linux/swap.h:9: In file included from include/linux/memcontrol.h:22: In file included from include/linux/writeback.h:14: In file included from include/linux/blk-cgroup.h:23: In file included from include/linux/blkdev.h:25: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr)); ~~ ^ include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu' #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x)) ^ include/uapi/linux/swab.h:119:21: note: expanded from macro '__swab32' ___constant_swab32(x) : \ ^ include/uapi/linux/swab.h:22:12: note: expanded from macro '___constant_swab32' (((__u32)(x) & (__u32)0xff00UL) >> 24))) ^ In file included from arch/s390/mm/init.c:20: In file included from include/linux/swap.h:9: In file included from include/linux/memcontrol.h:22: In file included from include/linux/writeback.h:14: In file included from include/linux/blk-cgroup.h:23: In file included from include/linux/blkdev.h:25: In file included from include/linux/scatterlist.h:9: In file included from arch/s390/include/asm/io.h:72: include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic] val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE +
