linux-kernel - Re: [PATCH v2 3/4] KVM: SVM: Add GHCB Accessor functions

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Date:   Fri, 31 Jul 2020 08:18:04 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Tom Lendacky <thomas.lendacky@....com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH v2 3/4] KVM: SVM: Add GHCB Accessor functions

On Thu, Jul 30, 2020 at 05:43:39PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.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 and to check the valid bitmap
> in KVM.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---
>  arch/x86/include/asm/svm.h | 46 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
> index 9a3e0b802716..8744817358bf 100644
> --- a/arch/x86/include/asm/svm.h
> +++ b/arch/x86/include/asm/svm.h
> @@ -341,4 +341,50 @@ struct __attribute__ ((__packed__)) vmcb {
>  
>  #define SVM_CR0_SELECTIVE_MASK (X86_CR0_TS | X86_CR0_MP)
>  
> +/* GHCB Accessor functions */
> +
> +#define GHB_BITMAP_IDX(field)								\
> +        (offsetof(struct vmcb_save_area, field) / sizeof(u64))
> +
> +#define GHCB_SET_VALID(ghcb, field)							\
> +	__set_bit(GHB_BITMAP_IDX(field), (unsigned long *)&(ghcb)->save.valid_bitmap);	\
> +
> +#define DEFINE_GHCB_ACCESSORS(field)							\
> +	static inline bool ghcb_##field##_is_valid(const struct ghcb *ghcb)		\
> +	{										\
> +		int idx = offsetof(struct vmcb_save_area, field) / sizeof(u64);		\

This should also use GHB_BITMAP_IDX.

> +		return test_bit(idx, (unsigned long *)&(ghcb)->save.valid_bitmap);	\
> +	}										\
> +											\
> +	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
>