| Message ID | 20170206145747.13885-5-sergey.dyasli@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> From: Sergey Dyasli [mailto:sergey.dyasli@citrix.com] > Sent: Monday, February 06, 2017 10:58 PM > > There is an issue with the original __vmread() in nested vmx mode: > emulation of a guest's VMREAD with invalid arguments leads to BUG(). > > Fix this by using vmread_safe() and reporting any kind of VMfail back > to the guest. > > A new safe versions of get_vvmcs() macro and related functions are > introduced because of new function signatures and lots of existing > users. > > Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> after reading this patch I realized my earlier ack to 3/4 might not hold, since now you have mismatched get/set pairs: get_vvmcs get_vvmcs_safe set_vvmcs suggest to also introduce a set_vvmcs_safe counterpart in 3/4, as there are still many existing callers on set_vvmcs which don't expect error. > --- > xen/arch/x86/hvm/vmx/vmcs.c | 9 +++++---- > xen/arch/x86/hvm/vmx/vvmx.c | 26 +++++++++++++++++++++++--- > xen/include/asm-x86/hvm/vmx/vmcs.h | 3 ++- > xen/include/asm-x86/hvm/vmx/vvmx.h | 7 +++++++ > 4 files changed, 37 insertions(+), 8 deletions(-) > > diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c > index 1d83a69..e04b002 100644 > --- a/xen/arch/x86/hvm/vmx/vmcs.c > +++ b/xen/arch/x86/hvm/vmx/vmcs.c > @@ -932,15 +932,16 @@ void virtual_vmcs_exit(const struct vcpu *v) > __vmptrld(cur); > } > > -u64 virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding) > +unsigned long virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding, > + u64 *val) > { > - u64 res; > + unsigned long ret; > > virtual_vmcs_enter(v); > - __vmread(vmcs_encoding, &res); > + ret = vmread_safe(vmcs_encoding, val); > virtual_vmcs_exit(v); > > - return res; > + return ret; > } > > unsigned long virtual_vmcs_vmwrite(const struct vcpu *v, u32 vmcs_encoding, > diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c > index 1a3d1d2..6fda44a 100644 > --- a/xen/arch/x86/hvm/vmx/vvmx.c > +++ b/xen/arch/x86/hvm/vmx/vvmx.c > @@ -261,7 +261,23 @@ u64 get_vvmcs_virtual(void *vvmcs, u32 vmcs_encoding) > > u64 get_vvmcs_real(const struct vcpu *v, u32 encoding) > { > - return virtual_vmcs_vmread(v, encoding); > + u64 val; > + > + virtual_vmcs_vmread(v, encoding, &val); > + > + return val; > +} > + > +unsigned long get_vvmcs_virtual_safe(void *vvmcs, u32 encoding, u64 *val) > +{ > + *val = get_vvmcs_virtual(vvmcs, encoding); > + > + return 0; > +} > + > +unsigned long get_vvmcs_real_safe(const struct vcpu *v, u32 encoding, u64 *val) > +{ > + return virtual_vmcs_vmread(v, encoding, val); > } > > unsigned long set_vvmcs_virtual(void *vvmcs, u32 vmcs_encoding, u64 val) > @@ -1710,13 +1726,17 @@ int nvmx_handle_vmread(struct cpu_user_regs *regs) > struct vmx_inst_decoded decode; > pagefault_info_t pfinfo; > u64 value = 0; > - int rc; > + unsigned long rc; > > rc = decode_vmx_inst(regs, &decode, NULL, 0); > if ( rc != X86EMUL_OKAY ) > return rc; > > - value = get_vvmcs(v, reg_read(regs, decode.reg2)); > + if ( (rc = get_vvmcs_safe(v, reg_read(regs, decode.reg2), &value)) ) > + { > + vmfail(regs, rc); > + return X86EMUL_OKAY; > + } > > switch ( decode.type ) { > case VMX_INST_MEMREG_TYPE_MEMORY: > diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h > b/xen/include/asm-x86/hvm/vmx/vmcs.h > index 72dc5fc..4f16250 100644 > --- a/xen/include/asm-x86/hvm/vmx/vmcs.h > +++ b/xen/include/asm-x86/hvm/vmx/vmcs.h > @@ -540,7 +540,8 @@ void vmx_clear_eoi_exit_bitmap(struct vcpu *v, u8 vector); > int vmx_check_msr_bitmap(unsigned long *msr_bitmap, u32 msr, int access_type); > void virtual_vmcs_enter(const struct vcpu *); > void virtual_vmcs_exit(const struct vcpu *); > -u64 virtual_vmcs_vmread(const struct vcpu *, u32 encoding); > +unsigned long virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding, > + u64 *val); > unsigned long virtual_vmcs_vmwrite(const struct vcpu *, u32 encoding, u64 val); > > static inline int vmx_add_guest_msr(u32 msr) > diff --git a/xen/include/asm-x86/hvm/vmx/vvmx.h > b/xen/include/asm-x86/hvm/vmx/vvmx.h > index d60e0bb..28e2503 100644 > --- a/xen/include/asm-x86/hvm/vmx/vvmx.h > +++ b/xen/include/asm-x86/hvm/vmx/vvmx.h > @@ -181,6 +181,8 @@ enum vvmcs_encoding_type { > > u64 get_vvmcs_virtual(void *vvmcs, u32 encoding); > u64 get_vvmcs_real(const struct vcpu *, u32 encoding); > +unsigned long get_vvmcs_virtual_safe(void *vvmcs, u32 encoding, u64 *val); > +unsigned long get_vvmcs_real_safe(const struct vcpu *, u32 encoding, u64 *val); > unsigned long set_vvmcs_virtual(void *vvmcs, u32 encoding, u64 val); > unsigned long set_vvmcs_real(const struct vcpu *, u32 encoding, u64 val); > > @@ -194,6 +196,11 @@ unsigned long set_vvmcs_real(const struct vcpu *, u32 encoding, > u64 val); > set_vvmcs_real(vcpu, encoding, val) : \ > set_vvmcs_virtual(vcpu_nestedhvm(vcpu).nv_vvmcx, encoding, val)) > > +#define get_vvmcs_safe(vcpu, encoding, val) \ > + (cpu_has_vmx_vmcs_shadowing ? \ > + get_vvmcs_real_safe(vcpu, encoding, val) : \ > + get_vvmcs_virtual_safe(vcpu_nestedhvm(vcpu).nv_vvmcx, encoding, val)) > + > uint64_t get_shadow_eptp(struct vcpu *v); > > void nvmx_destroy_vmcs(struct vcpu *v); > -- > 2.9.3
On Tue, 2017-02-07 at 06:52 +0000, Tian, Kevin wrote: > > From: Sergey Dyasli [mailto:sergey.dyasli@citrix.com] > > Sent: Monday, February 06, 2017 10:58 PM > > > > There is an issue with the original __vmread() in nested vmx mode: > > emulation of a guest's VMREAD with invalid arguments leads to BUG(). > > > > Fix this by using vmread_safe() and reporting any kind of VMfail back > > to the guest. > > > > A new safe versions of get_vvmcs() macro and related functions are > > introduced because of new function signatures and lots of existing > > users. > > > > Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> > > after reading this patch I realized my earlier ack to 3/4 might not hold, > since now you have mismatched get/set pairs: > > get_vvmcs > get_vvmcs_safe > set_vvmcs > > suggest to also introduce a set_vvmcs_safe counterpart in 3/4, as > there are still many existing callers on set_vvmcs which don't > expect error. It is true that my patch introduces a change in behaviour: invalid set_vvmcs() calls will silently fail instead of triggering BUG(). I agree it would be better to introduce set_vvmcs_safe() for now. -- Thanks, Sergey
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c index 1d83a69..e04b002 100644 --- a/xen/arch/x86/hvm/vmx/vmcs.c +++ b/xen/arch/x86/hvm/vmx/vmcs.c @@ -932,15 +932,16 @@ void virtual_vmcs_exit(const struct vcpu *v) __vmptrld(cur); } -u64 virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding) +unsigned long virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding, + u64 *val) { - u64 res; + unsigned long ret; virtual_vmcs_enter(v); - __vmread(vmcs_encoding, &res); + ret = vmread_safe(vmcs_encoding, val); virtual_vmcs_exit(v); - return res; + return ret; } unsigned long virtual_vmcs_vmwrite(const struct vcpu *v, u32 vmcs_encoding, diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c index 1a3d1d2..6fda44a 100644 --- a/xen/arch/x86/hvm/vmx/vvmx.c +++ b/xen/arch/x86/hvm/vmx/vvmx.c @@ -261,7 +261,23 @@ u64 get_vvmcs_virtual(void *vvmcs, u32 vmcs_encoding) u64 get_vvmcs_real(const struct vcpu *v, u32 encoding) { - return virtual_vmcs_vmread(v, encoding); + u64 val; + + virtual_vmcs_vmread(v, encoding, &val); + + return val; +} + +unsigned long get_vvmcs_virtual_safe(void *vvmcs, u32 encoding, u64 *val) +{ + *val = get_vvmcs_virtual(vvmcs, encoding); + + return 0; +} + +unsigned long get_vvmcs_real_safe(const struct vcpu *v, u32 encoding, u64 *val) +{ + return virtual_vmcs_vmread(v, encoding, val); } unsigned long set_vvmcs_virtual(void *vvmcs, u32 vmcs_encoding, u64 val) @@ -1710,13 +1726,17 @@ int nvmx_handle_vmread(struct cpu_user_regs *regs) struct vmx_inst_decoded decode; pagefault_info_t pfinfo; u64 value = 0; - int rc; + unsigned long rc; rc = decode_vmx_inst(regs, &decode, NULL, 0); if ( rc != X86EMUL_OKAY ) return rc; - value = get_vvmcs(v, reg_read(regs, decode.reg2)); + if ( (rc = get_vvmcs_safe(v, reg_read(regs, decode.reg2), &value)) ) + { + vmfail(regs, rc); + return X86EMUL_OKAY; + } switch ( decode.type ) { case VMX_INST_MEMREG_TYPE_MEMORY: diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h b/xen/include/asm-x86/hvm/vmx/vmcs.h index 72dc5fc..4f16250 100644 --- a/xen/include/asm-x86/hvm/vmx/vmcs.h +++ b/xen/include/asm-x86/hvm/vmx/vmcs.h @@ -540,7 +540,8 @@ void vmx_clear_eoi_exit_bitmap(struct vcpu *v, u8 vector); int vmx_check_msr_bitmap(unsigned long *msr_bitmap, u32 msr, int access_type); void virtual_vmcs_enter(const struct vcpu *); void virtual_vmcs_exit(const struct vcpu *); -u64 virtual_vmcs_vmread(const struct vcpu *, u32 encoding); +unsigned long virtual_vmcs_vmread(const struct vcpu *v, u32 vmcs_encoding, + u64 *val); unsigned long virtual_vmcs_vmwrite(const struct vcpu *, u32 encoding, u64 val); static inline int vmx_add_guest_msr(u32 msr) diff --git a/xen/include/asm-x86/hvm/vmx/vvmx.h b/xen/include/asm-x86/hvm/vmx/vvmx.h index d60e0bb..28e2503 100644 --- a/xen/include/asm-x86/hvm/vmx/vvmx.h +++ b/xen/include/asm-x86/hvm/vmx/vvmx.h @@ -181,6 +181,8 @@ enum vvmcs_encoding_type { u64 get_vvmcs_virtual(void *vvmcs, u32 encoding); u64 get_vvmcs_real(const struct vcpu *, u32 encoding); +unsigned long get_vvmcs_virtual_safe(void *vvmcs, u32 encoding, u64 *val); +unsigned long get_vvmcs_real_safe(const struct vcpu *, u32 encoding, u64 *val); unsigned long set_vvmcs_virtual(void *vvmcs, u32 encoding, u64 val); unsigned long set_vvmcs_real(const struct vcpu *, u32 encoding, u64 val); @@ -194,6 +196,11 @@ unsigned long set_vvmcs_real(const struct vcpu *, u32 encoding, u64 val); set_vvmcs_real(vcpu, encoding, val) : \ set_vvmcs_virtual(vcpu_nestedhvm(vcpu).nv_vvmcx, encoding, val)) +#define get_vvmcs_safe(vcpu, encoding, val) \ + (cpu_has_vmx_vmcs_shadowing ? \ + get_vvmcs_real_safe(vcpu, encoding, val) : \ + get_vvmcs_virtual_safe(vcpu_nestedhvm(vcpu).nv_vvmcx, encoding, val)) + uint64_t get_shadow_eptp(struct vcpu *v); void nvmx_destroy_vmcs(struct vcpu *v);
There is an issue with the original __vmread() in nested vmx mode: emulation of a guest's VMREAD with invalid arguments leads to BUG(). Fix this by using vmread_safe() and reporting any kind of VMfail back to the guest. A new safe versions of get_vvmcs() macro and related functions are introduced because of new function signatures and lots of existing users. Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> --- xen/arch/x86/hvm/vmx/vmcs.c | 9 +++++---- xen/arch/x86/hvm/vmx/vvmx.c | 26 +++++++++++++++++++++++--- xen/include/asm-x86/hvm/vmx/vmcs.h | 3 ++- xen/include/asm-x86/hvm/vmx/vvmx.h | 7 +++++++ 4 files changed, 37 insertions(+), 8 deletions(-)