Re: [PATCH v7 050/102] KVM: VMX: Split out guts of EPT violation to common/exposed function

Kai Huang
2022-07-08T10:25:38Z

On Mon, 2022-06-27 at 14:53 -0700, isaku.yamahata@intel.com wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> The difference of TDX EPT violation is how to retrieve information, GPA,
> and exit qualification. To share the code to handle EPT violation, split
> out the guts of EPT violation handler so that VMX/TDX exit handler can call
> it after retrieving GPA and exit qualification.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/vmx/common.h | 33 +++++++++++++++++++++++++++++++++
> arch/x86/kvm/vmx/vmx.c | 32 ++++++--------------------------
> 2 files changed, 39 insertions(+), 26 deletions(-)
> create mode 100644 arch/x86/kvm/vmx/common.h
>
> diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
> new file mode 100644
> index 000000000000..235908f3e044
> --- /dev/null
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __KVM_X86_VMX_COMMON_H
> +#define __KVM_X86_VMX_COMMON_H
> +
> +#include <linux/kvm_host.h>
> +
> +#include "mmu.h"
> +
> +static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
> + unsigned long exit_qualification)
> +{
> + u64 error_code;
> +
> + /* Is it a read fault? */
> + error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
> + ? PFERR_USER_MASK : 0;
> + /* Is it a write fault? */
> + error_code |= (exit_qualification & EPT_VIOLATION_ACC_WRITE)
> + ? PFERR_WRITE_MASK : 0;
> + /* Is it a fetch fault? */
> + error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
> + ? PFERR_FETCH_MASK : 0;
> + /* ept page table entry is present? */
> + error_code |= (exit_qualification & EPT_VIOLATION_RWX_MASK)
> + ? PFERR_PRESENT_MASK : 0;
> +
> + error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) != 0 ?
> + PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> +
> + return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
> +}
> +
> +#endif /* __KVM_X86_VMX_COMMON_H */
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index e3d304b14df0..2f1dc06aec3c 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -50,6 +50,7 @@
> #include <asm/vmx.h>
>
> #include "capabilities.h"
> +#include "common.h"
> #include "cpuid.h"
> #include "evmcs.h"
> #include "hyperv.h"
> @@ -5578,11 +5579,10 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
>
> static int handle_ept_violation(struct kvm_vcpu *vcpu)
> {
> - unsigned long exit_qualification;
> - gpa_t gpa;
> - u64 error_code;
> + unsigned long exit_qualification = vmx_get_exit_qual(vcpu);
> + gpa_t gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
>
> - exit_qualification = vmx_get_exit_qual(vcpu);
> + trace_kvm_page_fault(gpa, exit_qualification);
>
> /*
> * EPT violation happened while executing iret from NMI,
> @@ -5591,29 +5591,9 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
> * AAK134, BY25.
> */
> if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
> - enable_vnmi &&
> - (exit_qualification & INTR_INFO_UNBLOCK_NMI))
> + enable_vnmi && (exit_qualification & INTR_INFO_UNBLOCK_NMI))

Why this code change?

With this removed:

Reviewed-by: Kai Huang <kai.huang@intel.com>

> vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
>
> - gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
> - trace_kvm_page_fault(gpa, exit_qualification);
> -
> - /* Is it a read fault? */
> - error_code = (exit_qualification & EPT_VIOLATION_ACC_READ)
> - ? PFERR_USER_MASK : 0;
> - /* Is it a write fault? */
> - error_code |= (exit_qualification & EPT_VIOLATION_ACC_WRITE)
> - ? PFERR_WRITE_MASK : 0;
> - /* Is it a fetch fault? */
> - error_code |= (exit_qualification & EPT_VIOLATION_ACC_INSTR)
> - ? PFERR_FETCH_MASK : 0;
> - /* ept page table entry is present? */
> - error_code |= (exit_qualification & EPT_VIOLATION_RWX_MASK)
> - ? PFERR_PRESENT_MASK : 0;
> -
> - error_code |= (exit_qualification & EPT_VIOLATION_GVA_TRANSLATED) != 0 ?
> - PFERR_GUEST_FINAL_MASK : PFERR_GUEST_PAGE_MASK;
> -
> vcpu->arch.exit_qualification = exit_qualification;
>
> /*
> @@ -5627,7 +5607,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
> if (unlikely(allow_smaller_maxphyaddr && kvm_vcpu_is_illegal_gpa(vcpu, gpa)))
> return kvm_emulate_instruction(vcpu, 0);
>
> - return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
> + return __vmx_handle_ept_violation(vcpu, gpa, exit_qualification);
> }
>
> static int handle_ept_misconfig(struct kvm_vcpu *vcpu)