| Message ID | 6f8db92b-4391-c475-6335-7192b821dddb@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
Hi Balbir,
[auto build test ERROR on kvm/linux-next]
[also build test ERROR on v4.9-rc7 next-20161129]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Balbir-Singh/KVM-PPC-Patch-for-KVM-issue-in-real-mode/20161129-233307
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: powerpc-ppa8548_defconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=powerpc
All errors (new ones prefixed by >>):
In file included from arch/powerpc/include/asm/kvm_ppc.h:30:0,
from arch/powerpc/kernel/dbell.c:20:
>> include/linux/kvm_host.h:807:21: error: redefinition of 'kvm_arch_vzalloc'
static inline void *kvm_arch_vzalloc(unsigned long size)
^~~~~~~~~~~~~~~~
In file included from include/linux/kvm_host.h:37:0,
from arch/powerpc/include/asm/kvm_ppc.h:30,
from arch/powerpc/kernel/dbell.c:20:
arch/powerpc/include/asm/kvm_host.h:725:21: note: previous definition of 'kvm_arch_vzalloc' was here
static inline void *kvm_arch_vzalloc(unsigned long size)
^~~~~~~~~~~~~~~~
vim +/kvm_arch_vzalloc +807 include/linux/kvm_host.h
801 }
802 #endif
803
804 #ifdef __KVM_HAVE_ARCH_VZALLOC_OVERRIDE
805 static void *kvm_arch_vzalloc(unsigned long size);
806 #else
> 807 static inline void *kvm_arch_vzalloc(unsigned long size)
808 {
809 return vzalloc(size);
810 }
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index f15713a..efcdc1d 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -733,6 +733,24 @@ struct kvm_vcpu_arch { #define __KVM_HAVE_ARCH_WQP #define __KVM_HAVE_CREATE_DEVICE +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +#define __KVM_HAVE_ARCH_VZALLOC_OVERRIDE +#endif + +/* + * KVM uses some of these data structures -- the ones + * from kvzalloc() in real mode. If the data structure + * happens to come from a vmalloc'd range then its access + * in real mode will lead to problems due to the aliasing + * issue - (top 4 bits are ignore). + * A 0xd000+offset will point to a 0xc000+offset in realmode + * Hence we want our data structures from come from kmalloc'd + * regions, so that we don't have these aliasing issues + */ +static inline void *kvm_arch_vzalloc(unsigned long size) +{ + return kzalloc(size, GFP_KERNEL); +} static inline void kvm_arch_hardware_disable(void) {} static inline void kvm_arch_hardware_unsetup(void) {} diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 01c0b9c..0c88af5 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -19,6 +19,7 @@ #include <linux/preempt.h> #include <linux/msi.h> #include <linux/slab.h> +#include <linux/vmalloc.h> #include <linux/rcupdate.h> #include <linux/ratelimit.h> #include <linux/err.h> @@ -793,6 +794,16 @@ static inline bool kvm_arch_has_noncoherent_dma(struct kvm *kvm) return false; } #endif + +#ifdef __KVM_HAVE_ARCH_VZALLOC_OVERRIDE +static void *kvm_arch_vzalloc(unsigned long size); +#else +static inline void *kvm_arch_vzalloc(unsigned long size) +{ + return vzalloc(size); +} +#endif + #ifdef __KVM_HAVE_ARCH_ASSIGNED_DEVICE void kvm_arch_start_assignment(struct kvm *kvm); void kvm_arch_end_assignment(struct kvm *kvm); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index fbf04c0..57e3dca 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -689,7 +689,7 @@ static struct kvm *kvm_create_vm(unsigned long type) void *kvm_kvzalloc(unsigned long size) { if (size > PAGE_SIZE) - return vzalloc(size); + return kvm_arch_vzalloc(size); else return kzalloc(size, GFP_KERNEL); }
Some KVM functions for book3s_hv are called in real mode. In real mode the top 4 bits of the address space are ignored, hence an address beginning with 0xc0000000+offset is the same as 0xd0000000+offset. The issue was observed when a kvm memslot resolution lead to random values when accessed from kvmppc_h_enter(). The issue is hit if the KVM host is running with a page size of 4K, since kvzalloc() looks at size < PAGE_SIZE. On systems with 64K the issue is not observed easily, it largely depends on the size of the structure being allocated. The proposed fix moves all KVM allocations for book3s_hv to kzalloc() until all structures used in real mode are audited. For safety allocations are moved to kmalloc space. The impact is a large allocation on systems with 4K page size. Signed-off-by: Balbir Singh <bsingharora@gmail.com> --- arch/powerpc/include/asm/kvm_host.h | 18 ++++++++++++++++++ include/linux/kvm_host.h | 11 +++++++++++ virt/kvm/kvm_main.c | 2 +- 3 files changed, 30 insertions(+), 1 deletion(-)