From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Joerg Roedel <jroedel@suse.de>
Subject: Re: [PATCH 3/4] KVM: SVM: Add GHCB Accessor functions
Date: Wed, 29 Jul 2020 08:43:28 -0700 [thread overview]
Message-ID: <20200729154328.GC27751@linux.intel.com> (raw)
In-Reply-To: <20200729132234.2346-4-joro@8bytes.org>
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
>
next prev parent reply other threads:[~2020-07-29 15:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-29 13:22 [PATCH 0/4] KVM: SVM: SEV-ES groundwork Joerg Roedel
2020-07-29 13:22 ` [PATCH 1/4] KVM: SVM: nested: Don't allocate VMCB structures on stack Joerg Roedel
2020-07-29 15:14 ` Sean Christopherson
2020-07-30 12:38 ` Joerg Roedel
2020-07-29 13:22 ` [PATCH 2/4] KVM: SVM: Add GHCB definitions Joerg Roedel
2020-07-29 13:22 ` [PATCH 3/4] KVM: SVM: Add GHCB Accessor functions Joerg Roedel
2020-07-29 15:43 ` Sean Christopherson [this message]
2020-07-30 13:05 ` Joerg Roedel
2020-07-29 13:22 ` [PATCH 4/4] KVM: SVM: Use __packed shorthand Joerg Roedel
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