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Date: Mon, 21 Dec 2020 14:00:52 -0800
From: Krish Sadhukhan <krish.sadhukhan@...cle.com>
To: Uros Bizjak <ubizjak@...il.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH v3] KVM/x86: Move definition of __ex to x86.h
On 12/21/20 11:48 AM, Uros Bizjak wrote:
> Merge __kvm_handle_fault_on_reboot with its sole user
> and move the definition of __ex to a common include to be
> shared between VMX and SVM.
>
> v2: Rebase to the latest kvm/queue.
>
> v3: Incorporate changes from review comments.
>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Uros Bizjak <ubizjak@...il.com>
> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@...cle.com>
> ---
> arch/x86/include/asm/kvm_host.h | 25 -------------------------
> arch/x86/kvm/svm/sev.c | 2 --
> arch/x86/kvm/svm/svm.c | 2 --
> arch/x86/kvm/vmx/vmx.c | 4 +---
> arch/x86/kvm/vmx/vmx_ops.h | 4 +---
> arch/x86/kvm/x86.h | 24 ++++++++++++++++++++++++
> 6 files changed, 26 insertions(+), 35 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 39707e72b062..a78e4b1a5d77 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1634,31 +1634,6 @@ enum {
> #define kvm_arch_vcpu_memslots_id(vcpu) ((vcpu)->arch.hflags & HF_SMM_MASK ? 1 : 0)
> #define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, (role).smm)
>
> -asmlinkage void kvm_spurious_fault(void);
> -
> -/*
> - * Hardware virtualization extension instructions may fault if a
> - * reboot turns off virtualization while processes are running.
> - * Usually after catching the fault we just panic; during reboot
> - * instead the instruction is ignored.
> - */
> -#define __kvm_handle_fault_on_reboot(insn) \
> - "666: \n\t" \
> - insn "\n\t" \
> - "jmp 668f \n\t" \
> - "667: \n\t" \
> - "1: \n\t" \
> - ".pushsection .discard.instr_begin \n\t" \
> - ".long 1b - . \n\t" \
> - ".popsection \n\t" \
> - "call kvm_spurious_fault \n\t" \
> - "1: \n\t" \
> - ".pushsection .discard.instr_end \n\t" \
> - ".long 1b - . \n\t" \
> - ".popsection \n\t" \
> - "668: \n\t" \
> - _ASM_EXTABLE(666b, 667b)
> -
> #define KVM_ARCH_WANT_MMU_NOTIFIER
> int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
> unsigned flags);
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index e57847ff8bd2..ba492b6d37a0 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -25,8 +25,6 @@
> #include "cpuid.h"
> #include "trace.h"
>
> -#define __ex(x) __kvm_handle_fault_on_reboot(x)
> -
> static u8 sev_enc_bit;
> static int sev_flush_asids(void);
> static DECLARE_RWSEM(sev_deactivate_lock);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 941e5251e13f..733d9f98a121 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -42,8 +42,6 @@
>
> #include "svm.h"
>
> -#define __ex(x) __kvm_handle_fault_on_reboot(x)
> -
> MODULE_AUTHOR("Qumranet");
> MODULE_LICENSE("GPL");
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 75c9c6a0a3a4..b82f2689f2d7 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -2320,9 +2320,7 @@ static void vmclear_local_loaded_vmcss(void)
> }
>
>
> -/* Just like cpu_vmxoff(), but with the __kvm_handle_fault_on_reboot()
> - * tricks.
> - */
> +/* Just like cpu_vmxoff(), but with the fault handling. */
> static void kvm_cpu_vmxoff(void)
> {
> asm volatile (__ex("vmxoff"));
> diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
> index 692b0c31c9c8..7e3cb53c413f 100644
> --- a/arch/x86/kvm/vmx/vmx_ops.h
> +++ b/arch/x86/kvm/vmx/vmx_ops.h
> @@ -4,13 +4,11 @@
>
> #include <linux/nospec.h>
>
> -#include <asm/kvm_host.h>
> #include <asm/vmx.h>
>
> #include "evmcs.h"
> #include "vmcs.h"
> -
> -#define __ex(x) __kvm_handle_fault_on_reboot(x)
> +#include "x86.h"
>
> asmlinkage void vmread_error(unsigned long field, bool fault);
> __attribute__((regparm(0))) void vmread_error_trampoline(unsigned long field,
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index c5ee0f5ce0f1..5b16d2b5c3bc 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -8,6 +8,30 @@
> #include "kvm_cache_regs.h"
> #include "kvm_emulate.h"
>
> +asmlinkage void kvm_spurious_fault(void);
> +
> +/*
> + * Handle a fault on a hardware virtualization (VMX or SVM) instruction.
> + *
> + * Hardware virtualization extension instructions may fault if a reboot turns
> + * off virtualization while processes are running. Usually after catching the
> + * fault we just panic; during reboot instead the instruction is ignored.
> + */
> +#define __ex(insn) \
While the previous name was too elaborate, this new name is very
cryptic. Unless we are saving for space, it's better to give a somewhat
descriptive name.
> + "666: " insn "\n" \
> + " jmp 669f\n" \
> + "667:\n" \
> + " .pushsection .discard.instr_begin\n" \
> + " .long 667b - .\n" \
> + " .popsection\n" \
> + " call kvm_spurious_fault\n" \
> + "668:\n" \
> + " .pushsection .discard.instr_end\n" \
> + " .long 668b - .\n" \
> + " .popsection\n" \
> + "669:\n" \
> + _ASM_EXTABLE(666b, 667b)
> +
> #define KVM_DEFAULT_PLE_GAP 128
> #define KVM_VMX_DEFAULT_PLE_WINDOW 4096
> #define KVM_DEFAULT_PLE_WINDOW_GROW 2
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