| Message ID | 20250307164123.1613414-7-chao.gao@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce CET supervisor state support | expand |
On 3/7/25 08:41, Chao Gao wrote: > From: Yang Weijiang <weijiang.yang@intel.com> > > Use the new fpu_guest_cfg to initialize guest permissions. Background, please. What are the guest permissions currently set to? Why does it need to change? > Note fpu_guest_cfg and fpu_kernel_cfg remain the same for now. So there > is no functional change. > > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> > [Gao Chao: Extrace this from the previous patch ] > Signed-off-by: Chao Gao <chao.gao@intel.com> > --- > arch/x86/kernel/fpu/core.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c > index b0c1ef40d105..d7ae684adbad 100644 > --- a/arch/x86/kernel/fpu/core.c > +++ b/arch/x86/kernel/fpu/core.c > @@ -534,8 +534,15 @@ void fpstate_reset(struct fpu *fpu) > fpu->perm.__state_perm = fpu_kernel_cfg.default_features; > fpu->perm.__state_size = fpu_kernel_cfg.default_size; > fpu->perm.__user_state_size = fpu_user_cfg.default_size; > - /* Same defaults for guests */ > - fpu->guest_perm = fpu->perm; > + > + /* Guest permission settings */ > + fpu->guest_perm.__state_perm = fpu_guest_cfg.default_features; > + fpu->guest_perm.__state_size = fpu_guest_cfg.default_size; > + /* > + * Set guest's __user_state_size to fpu_user_cfg.default_size so that > + * existing uAPIs can still work. > + */ I suspect that readers here will understand that this line: > + fpu->guest_perm.__user_state_size = fpu_user_cfg.default_size; > } means "Set guest's __user_state_size to fpu_user_cfg.default_size". The comment basically just literally restates what the code does. That part of the comment doesn't add value.
On Fri, Mar 07, 2025 at 10:14:19AM -0800, Dave Hansen wrote: >On 3/7/25 08:41, Chao Gao wrote: >> From: Yang Weijiang <weijiang.yang@intel.com> >> >> Use the new fpu_guest_cfg to initialize guest permissions. > >Background, please. > >What are the guest permissions currently set to? Why does it need to change? Ok. Will add: Currently, fpu->guest_perm is copied from fpu->perm, which is derived from fpu_kernel_cfg. To separate the guest FPU from the kernel FPU, switch to use the new fpu_guest_cfg to initialize guest permissions. This ensures that any future changes to fpu_guest_cfg will automatically update the guest permissions The __user_state_size is tied to existing uAPIs, so it remains unchanged. > >> Note fpu_guest_cfg and fpu_kernel_cfg remain the same for now. So there >> is no functional change. >> >> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> >> [Gao Chao: Extrace this from the previous patch ] >> Signed-off-by: Chao Gao <chao.gao@intel.com> >> --- >> arch/x86/kernel/fpu/core.c | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c >> index b0c1ef40d105..d7ae684adbad 100644 >> --- a/arch/x86/kernel/fpu/core.c >> +++ b/arch/x86/kernel/fpu/core.c >> @@ -534,8 +534,15 @@ void fpstate_reset(struct fpu *fpu) >> fpu->perm.__state_perm = fpu_kernel_cfg.default_features; >> fpu->perm.__state_size = fpu_kernel_cfg.default_size; >> fpu->perm.__user_state_size = fpu_user_cfg.default_size; >> - /* Same defaults for guests */ >> - fpu->guest_perm = fpu->perm; >> + >> + /* Guest permission settings */ >> + fpu->guest_perm.__state_perm = fpu_guest_cfg.default_features; >> + fpu->guest_perm.__state_size = fpu_guest_cfg.default_size; >> + /* >> + * Set guest's __user_state_size to fpu_user_cfg.default_size so that >> + * existing uAPIs can still work. >> + */ > >I suspect that readers here will understand that this line: > >> + fpu->guest_perm.__user_state_size = fpu_user_cfg.default_size; >> } > >means "Set guest's __user_state_size to fpu_user_cfg.default_size". The >comment basically just literally restates what the code does. That part >of the comment doesn't add value. Will drop this useless comment.
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index b0c1ef40d105..d7ae684adbad 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -534,8 +534,15 @@ void fpstate_reset(struct fpu *fpu) fpu->perm.__state_perm = fpu_kernel_cfg.default_features; fpu->perm.__state_size = fpu_kernel_cfg.default_size; fpu->perm.__user_state_size = fpu_user_cfg.default_size; - /* Same defaults for guests */ - fpu->guest_perm = fpu->perm; + + /* Guest permission settings */ + fpu->guest_perm.__state_perm = fpu_guest_cfg.default_features; + fpu->guest_perm.__state_size = fpu_guest_cfg.default_size; + /* + * Set guest's __user_state_size to fpu_user_cfg.default_size so that + * existing uAPIs can still work. + */ + fpu->guest_perm.__user_state_size = fpu_user_cfg.default_size; } static inline void fpu_inherit_perms(struct fpu *dst_fpu)