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[3/4] KVM: SVM: Add GHCB Accessor functions

Message ID 20200729132234.2346-4-joro@8bytes.org (mailing list archive)
State New, archived
Headers show
Series KVM: SVM: SEV-ES groundwork | expand

Commit Message

Joerg Roedel July 29, 2020, 1:22 p.m. UTC 
From: Joerg Roedel <jroedel@suse.de>

Building a correct GHCB for the hypervisor requires setting valid bits
in the GHCB. Simplify that process by providing accessor functions to
set values and to update the valid bitmap.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/include/asm/svm.h | 61 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

Comments

Sean Christopherson July 29, 2020, 3:43 p.m. UTC | #1 
On Wed, Jul 29, 2020 at 03:22:33PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> Building a correct GHCB for the hypervisor requires setting valid bits
> in the GHCB. Simplify that process by providing accessor functions to
> set values and to update the valid bitmap.
> 
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>  arch/x86/include/asm/svm.h | 61 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 9a3e0b802716..0420250b008b 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -341,4 +341,65 @@ struct __attribute__ ((__packed__)) vmcb {
>  
>  #define SVM_CR0_SELECTIVE_MASK (X86_CR0_TS | X86_CR0_MP)
>  
> +/* GHCB Accessor functions */
> +
> +#define DEFINE_GHCB_INDICES(field)					\
> +	u16 idx = offsetof(struct vmcb_save_area, field) / 8;		\

Using sizeof(u64) instead of '8' would be helpful here.

> +	u16 byte_idx  = idx / 8;					\
> +	u16 bit_idx   = idx % 8;					\

Oof.  I love macro frameworks as much as the next person, but declaring
local variables in a macro like this is nasty.

> +	BUILD_BUG_ON(byte_idx > ARRAY_SIZE(ghcb->save.valid_bitmap));
> +
> +#define GHCB_SET_VALID(ghcb, field)					\
> +	{								\
> +		DEFINE_GHCB_INDICES(field)				\
> +		(ghcb)->save.valid_bitmap[byte_idx] |= BIT(bit_idx);	\

Rather than manually calculate the byte/bit indices just use __set_bit()
and test_bit().  That will also solve the variable declaration issue.

E.g.

#define GHB_BITMAP_IDX(field)		\
	(offsetof(struct vmcb_save_area, (field)) / sizeof(u64))

#define GHCB_SET_VALID(ghcb, field)	\
	__set_bit(GHCB_BITMAP_IDX(field), (unsigned long *)&ghcb->save.valid_bitmap)

Or alternatively drop GHCB_SET_VALID() and just open code the two users.

> +	}
> +
> +#define DEFINE_GHCB_SETTER(field)					\
> +	static inline void						\
> +	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
> +	{								\
> +		GHCB_SET_VALID(ghcb, field)				\
> +		(ghcb)->save.field = value;				\


The ghcb doesn't need to be wrapped in (), it's a parameter to a function.
Same comment for the below usage.

> +	}
> +
> +#define DEFINE_GHCB_ACCESSORS(field)					\
> +	static inline bool ghcb_is_valid_##field(const struct ghcb *ghcb)	\

I'd prefer to follow the naming of the arch reg accessors, i.e.

	static inline bool ghcb_##field##_is_valid(...)

to pair with

	kvm_##lname##_read
	kvm_##lname##_write

And because ghcb_is_valid_rip() reads a bit weird, e.g. IMO is more likely
to be read as "does the RIP in the GHCB hold a valid (canonical) value",
versus ghcb_rip_is_valid() reading as "is RIP valid in the GHCB".

> +	{								\
> +		DEFINE_GHCB_INDICES(field)				\
> +		return !!((ghcb)->save.valid_bitmap[byte_idx]		\
> +						& BIT(bit_idx));	\
> +	}								\
> +									\
> +	static inline void						\
> +	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
> +	{								\
> +		GHCB_SET_VALID(ghcb, field)				\
> +		(ghcb)->save.field = value;				\

> +	}
> +
> +DEFINE_GHCB_ACCESSORS(cpl)
> +DEFINE_GHCB_ACCESSORS(rip)
> +DEFINE_GHCB_ACCESSORS(rsp)
> +DEFINE_GHCB_ACCESSORS(rax)
> +DEFINE_GHCB_ACCESSORS(rcx)
> +DEFINE_GHCB_ACCESSORS(rdx)
> +DEFINE_GHCB_ACCESSORS(rbx)
> +DEFINE_GHCB_ACCESSORS(rbp)
> +DEFINE_GHCB_ACCESSORS(rsi)
> +DEFINE_GHCB_ACCESSORS(rdi)
> +DEFINE_GHCB_ACCESSORS(r8)
> +DEFINE_GHCB_ACCESSORS(r9)
> +DEFINE_GHCB_ACCESSORS(r10)
> +DEFINE_GHCB_ACCESSORS(r11)
> +DEFINE_GHCB_ACCESSORS(r12)
> +DEFINE_GHCB_ACCESSORS(r13)
> +DEFINE_GHCB_ACCESSORS(r14)
> +DEFINE_GHCB_ACCESSORS(r15)
> +DEFINE_GHCB_ACCESSORS(sw_exit_code)
> +DEFINE_GHCB_ACCESSORS(sw_exit_info_1)
> +DEFINE_GHCB_ACCESSORS(sw_exit_info_2)
> +DEFINE_GHCB_ACCESSORS(sw_scratch)
> +DEFINE_GHCB_ACCESSORS(xcr0)
> +
>  #endif
> -- 
> 2.17.1
>
Joerg Roedel July 30, 2020, 1:05 p.m. UTC | #2 
On Wed, Jul 29, 2020 at 08:43:28AM -0700, Sean Christopherson wrote:
> Rather than manually calculate the byte/bit indices just use __set_bit()
> and test_bit().  That will also solve the variable declaration issue.
> 
> E.g.
> 
> #define GHB_BITMAP_IDX(field)		\
> 	(offsetof(struct vmcb_save_area, (field)) / sizeof(u64))
> 
> #define GHCB_SET_VALID(ghcb, field)	\
> 	__set_bit(GHCB_BITMAP_IDX(field), (unsigned long *)&ghcb->save.valid_bitmap)
> 
> Or alternatively drop GHCB_SET_VALID() and just open code the two users.

Thanks for your suggestions, I updated the patch and will do some
testing before re-posting.

Regards,

	Joerg

> 
> > +	}
> > +
> > +#define DEFINE_GHCB_SETTER(field)					\
> > +	static inline void						\
> > +	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
> > +	{								\
> > +		GHCB_SET_VALID(ghcb, field)				\
> > +		(ghcb)->save.field = value;				\
> 
> 
> The ghcb doesn't need to be wrapped in (), it's a parameter to a function.
> Same comment for the below usage.
> 
> > +	}
> > +
> > +#define DEFINE_GHCB_ACCESSORS(field)					\
> > +	static inline bool ghcb_is_valid_##field(const struct ghcb *ghcb)	\
> 
> I'd prefer to follow the naming of the arch reg accessors, i.e.
> 
> 	static inline bool ghcb_##field##_is_valid(...)
> 
> to pair with
> 
> 	kvm_##lname##_read
> 	kvm_##lname##_write
> 
> And because ghcb_is_valid_rip() reads a bit weird, e.g. IMO is more likely
> to be read as "does the RIP in the GHCB hold a valid (canonical) value",
> versus ghcb_rip_is_valid() reading as "is RIP valid in the GHCB".
> 
> > +	{								\
> > +		DEFINE_GHCB_INDICES(field)				\
> > +		return !!((ghcb)->save.valid_bitmap[byte_idx]		\
> > +						& BIT(bit_idx));	\
> > +	}								\
> > +									\
> > +	static inline void						\
> > +	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
> > +	{								\
> > +		GHCB_SET_VALID(ghcb, field)				\
> > +		(ghcb)->save.field = value;				\
> 
> > +	}
> > +
> > +DEFINE_GHCB_ACCESSORS(cpl)
> > +DEFINE_GHCB_ACCESSORS(rip)
> > +DEFINE_GHCB_ACCESSORS(rsp)
> > +DEFINE_GHCB_ACCESSORS(rax)
> > +DEFINE_GHCB_ACCESSORS(rcx)
> > +DEFINE_GHCB_ACCESSORS(rdx)
> > +DEFINE_GHCB_ACCESSORS(rbx)
> > +DEFINE_GHCB_ACCESSORS(rbp)
> > +DEFINE_GHCB_ACCESSORS(rsi)
> > +DEFINE_GHCB_ACCESSORS(rdi)
> > +DEFINE_GHCB_ACCESSORS(r8)
> > +DEFINE_GHCB_ACCESSORS(r9)
> > +DEFINE_GHCB_ACCESSORS(r10)
> > +DEFINE_GHCB_ACCESSORS(r11)
> > +DEFINE_GHCB_ACCESSORS(r12)
> > +DEFINE_GHCB_ACCESSORS(r13)
> > +DEFINE_GHCB_ACCESSORS(r14)
> > +DEFINE_GHCB_ACCESSORS(r15)
> > +DEFINE_GHCB_ACCESSORS(sw_exit_code)
> > +DEFINE_GHCB_ACCESSORS(sw_exit_info_1)
> > +DEFINE_GHCB_ACCESSORS(sw_exit_info_2)
> > +DEFINE_GHCB_ACCESSORS(sw_scratch)
> > +DEFINE_GHCB_ACCESSORS(xcr0)
> > +
> >  #endif
> > -- 
> > 2.17.1
> >
diff mbox series

Patch

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 9a3e0b802716..0420250b008b 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -341,4 +341,65 @@  struct __attribute__ ((__packed__)) vmcb {
 
 #define SVM_CR0_SELECTIVE_MASK (X86_CR0_TS | X86_CR0_MP)
 
+/* GHCB Accessor functions */
+
+#define DEFINE_GHCB_INDICES(field)					\
+	u16 idx = offsetof(struct vmcb_save_area, field) / 8;		\
+	u16 byte_idx  = idx / 8;					\
+	u16 bit_idx   = idx % 8;					\
+	BUILD_BUG_ON(byte_idx > ARRAY_SIZE(ghcb->save.valid_bitmap));
+
+#define GHCB_SET_VALID(ghcb, field)					\
+	{								\
+		DEFINE_GHCB_INDICES(field)				\
+		(ghcb)->save.valid_bitmap[byte_idx] |= BIT(bit_idx);	\
+	}
+
+#define DEFINE_GHCB_SETTER(field)					\
+	static inline void						\
+	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
+	{								\
+		GHCB_SET_VALID(ghcb, field)				\
+		(ghcb)->save.field = value;				\
+	}
+
+#define DEFINE_GHCB_ACCESSORS(field)					\
+	static inline bool ghcb_is_valid_##field(const struct ghcb *ghcb)	\
+	{								\
+		DEFINE_GHCB_INDICES(field)				\
+		return !!((ghcb)->save.valid_bitmap[byte_idx]		\
+						& BIT(bit_idx));	\
+	}								\
+									\
+	static inline void						\
+	ghcb_set_##field(struct ghcb *ghcb, u64 value)			\
+	{								\
+		GHCB_SET_VALID(ghcb, field)				\
+		(ghcb)->save.field = value;				\
+	}
+
+DEFINE_GHCB_ACCESSORS(cpl)
+DEFINE_GHCB_ACCESSORS(rip)
+DEFINE_GHCB_ACCESSORS(rsp)
+DEFINE_GHCB_ACCESSORS(rax)
+DEFINE_GHCB_ACCESSORS(rcx)
+DEFINE_GHCB_ACCESSORS(rdx)
+DEFINE_GHCB_ACCESSORS(rbx)
+DEFINE_GHCB_ACCESSORS(rbp)
+DEFINE_GHCB_ACCESSORS(rsi)
+DEFINE_GHCB_ACCESSORS(rdi)
+DEFINE_GHCB_ACCESSORS(r8)
+DEFINE_GHCB_ACCESSORS(r9)
+DEFINE_GHCB_ACCESSORS(r10)
+DEFINE_GHCB_ACCESSORS(r11)
+DEFINE_GHCB_ACCESSORS(r12)
+DEFINE_GHCB_ACCESSORS(r13)
+DEFINE_GHCB_ACCESSORS(r14)
+DEFINE_GHCB_ACCESSORS(r15)
+DEFINE_GHCB_ACCESSORS(sw_exit_code)
+DEFINE_GHCB_ACCESSORS(sw_exit_info_1)
+DEFINE_GHCB_ACCESSORS(sw_exit_info_2)
+DEFINE_GHCB_ACCESSORS(sw_scratch)
+DEFINE_GHCB_ACCESSORS(xcr0)
+
 #endif