| Message ID | 20210202223416.2702336-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: SVM: Use 'unsigned long' for the physical address passed to VMSAVE | expand |
On Tue, Feb 02, 2021, Sean Christopherson wrote: > Take an 'unsigned long' instead of 'hpa_t' in the recently added vmsave() > helper, as loading a 64-bit GPR isn't possible in 32-bit mode. This is > properly reflected in the SVM ISA, which explicitly states that VMSAVE, > VMLOAD, VMRUN, etc... consume rAX based on the effective address size. > > Don't bother with a WARN to detect breakage on 32-bit KVM, the VMCB PA is > stored as an 'unsigned long', i.e. the bad address is long since gone. > Not to mention that a 32-bit kernel is completely hosed if alloc_page() > hands out pages in high memory. > > Reported-by: kernel test robot <lkp@intel.com> > Cc: Robert Hu <robert.hu@intel.com> > Cc: Farrah Chen <farrah.chen@intel.com> > Cc: Danmei Wei <danmei.wei@intel.com> > Cc: Tom Lendacky <Thomas.Lendacky@amd.com> > Signed-off-by: Sean Christopherson <seanjc@google.com> Forgot got the Fixes tag. Or just squash this. Fixes: f84a54c04540 ("KVM: SVM: Use asm goto to handle unexpected #UD on SVM instructions") > --- > arch/x86/kvm/svm/svm_ops.h | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h > index 0c8377aee52c..9f007bc8409a 100644 > --- a/arch/x86/kvm/svm/svm_ops.h > +++ b/arch/x86/kvm/svm/svm_ops.h > @@ -51,7 +51,12 @@ static inline void invlpga(unsigned long addr, u32 asid) > svm_asm2(invlpga, "c"(asid), "a"(addr)); > } > > -static inline void vmsave(hpa_t pa) > +/* > + * Despite being a physical address, the portion of rAX that is consumed by > + * VMSAVE, VMLOAD, etc... is still controlled by the effective address size, > + * hence 'unsigned long' instead of 'hpa_t'. > + */ > +static inline void vmsave(unsigned long pa) > { > svm_asm1(vmsave, "a" (pa), "memory"); > } > -- > 2.30.0.365.g02bc693789-goog >
On 02/02/21 23:34, Sean Christopherson wrote: > diff --git a/arch/x86/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h > index 0c8377aee52c..9f007bc8409a 100644 > --- a/arch/x86/kvm/svm/svm_ops.h > +++ b/arch/x86/kvm/svm/svm_ops.h > @@ -51,7 +51,12 @@ static inline void invlpga(unsigned long addr, u32 asid) > svm_asm2(invlpga, "c"(asid), "a"(addr)); > } > > -static inline void vmsave(hpa_t pa) > +/* > + * Despite being a physical address, the portion of rAX that is consumed by > + * VMSAVE, VMLOAD, etc... is still controlled by the effective address size, > + * hence 'unsigned long' instead of 'hpa_t'. > + */ > +static inline void vmsave(unsigned long pa) > { > svm_asm1(vmsave, "a" (pa), "memory"); > } > -- > 2.30.0.365.g02bc693789-goog > Squashed, thanks. Paolo
diff --git a/arch/x86/kvm/svm/svm_ops.h b/arch/x86/kvm/svm/svm_ops.h index 0c8377aee52c..9f007bc8409a 100644 --- a/arch/x86/kvm/svm/svm_ops.h +++ b/arch/x86/kvm/svm/svm_ops.h @@ -51,7 +51,12 @@ static inline void invlpga(unsigned long addr, u32 asid) svm_asm2(invlpga, "c"(asid), "a"(addr)); } -static inline void vmsave(hpa_t pa) +/* + * Despite being a physical address, the portion of rAX that is consumed by + * VMSAVE, VMLOAD, etc... is still controlled by the effective address size, + * hence 'unsigned long' instead of 'hpa_t'. + */ +static inline void vmsave(unsigned long pa) { svm_asm1(vmsave, "a" (pa), "memory"); }
Take an 'unsigned long' instead of 'hpa_t' in the recently added vmsave() helper, as loading a 64-bit GPR isn't possible in 32-bit mode. This is properly reflected in the SVM ISA, which explicitly states that VMSAVE, VMLOAD, VMRUN, etc... consume rAX based on the effective address size. Don't bother with a WARN to detect breakage on 32-bit KVM, the VMCB PA is stored as an 'unsigned long', i.e. the bad address is long since gone. Not to mention that a 32-bit kernel is completely hosed if alloc_page() hands out pages in high memory. Reported-by: kernel test robot <lkp@intel.com> Cc: Robert Hu <robert.hu@intel.com> Cc: Farrah Chen <farrah.chen@intel.com> Cc: Danmei Wei <danmei.wei@intel.com> Cc: Tom Lendacky <Thomas.Lendacky@amd.com> Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/svm/svm_ops.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)