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x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM 

Provide a wrapper for expanding the guest fpstate buffer according
to requested xfeatures. KVM wants to call this wrapper to manage
any dynamic xstate used by the guest.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220105123532.12586-8-yang.zhong@intel.com>
[Remove unnecessary 32-bit check. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-01-05 04:35:18 -08:00 committed by Paolo Bonzini
parent c270ce393d
commit 0781d60f65
2 changed files with 23 additions and 0 deletions
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1
arch/x86/include/asm/fpu/api.h
View File

@ -138,6 +138,7 @@ extern inline u64 xstate_get_guest_group_perm(void);
extern bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu);
extern void fpu_free_guest_fpstate(struct fpu_guest *gfpu);
extern int fpu_swap_kvm_fpstate(struct fpu_guest *gfpu, bool enter_guest);
extern int fpu_enable_guest_xfd_features(struct fpu_guest *guest_fpu, u64 xfeatures);
extern void fpu_copy_guest_fpstate_to_uabi(struct fpu_guest *gfpu, void *buf, unsigned int size, u32 pkru);
extern int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, u64 xcr0, u32 *vpkru);

22
arch/x86/kernel/fpu/core.c
View File

@ -261,6 +261,28 @@ void fpu_free_guest_fpstate(struct fpu_guest *gfpu)
}
EXPORT_SYMBOL_GPL(fpu_free_guest_fpstate);
/*
* fpu_enable_guest_xfd_features - Check xfeatures against guest perm and enable
* @guest_fpu: Pointer to the guest FPU container
* @xfeatures: Features requested by guest CPUID
*
* Enable all dynamic xfeatures according to guest perm and requested CPUID.
*
* Return: 0 on success, error code otherwise
*/
int fpu_enable_guest_xfd_features(struct fpu_guest *guest_fpu, u64 xfeatures)
{
lockdep_assert_preemption_enabled();
/* Nothing to do if all requested features are already enabled. */
xfeatures &= ~guest_fpu->xfeatures;
if (!xfeatures)
return 0;
return __xfd_enable_feature(xfeatures, guest_fpu);
}
EXPORT_SYMBOL_GPL(fpu_enable_guest_xfd_features);
int fpu_swap_kvm_fpstate(struct fpu_guest *guest_fpu, bool enter_guest)
{
struct fpstate *guest_fps = guest_fpu->fpstate;