LinuxLists.cc - [PATCH 01/21] KVM: x86: Split core of hypercall emulation to helper function

2024-02-27 23:22:55

Subject: [PATCH 01/21] KVM: x86: Split core of hypercall emulation to helper function

From: Sean Christopherson <[email protected]>

By necessity, TDX will use a different register ABI for hypercalls.
Break out the core functionality so that it may be reused for TDX.

Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Isaku Yamahata <[email protected]>
Message-Id: <5134caa55ac3dec33fb2addb5545b52b3b52db02.1705965635.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <[email protected]>
---
arch/x86/include/asm/kvm_host.h | 4 +++
arch/x86/kvm/x86.c | 56 ++++++++++++++++++++++-----------
2 files changed, 42 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 724a0c778f79..85dc0f7d09e3 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2133,6 +2133,10 @@ static inline void kvm_clear_apicv_inhibit(struct kvm *kvm,
kvm_set_or_clear_apicv_inhibit(kvm, reason, false);
}

+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+ unsigned long a0, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ int op_64_bit, int cpl);
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);

int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b9dfe3179332..f10a5a617120 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10046,26 +10046,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu)
return kvm_skip_emulated_instruction(vcpu);
}

-int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+ unsigned long a0, unsigned long a1,
+ unsigned long a2, unsigned long a3,
+ int op_64_bit, int cpl)
{
- unsigned long nr, a0, a1, a2, a3, ret;
- int op_64_bit;
-
- if (kvm_xen_hypercall_enabled(vcpu->kvm))
- return kvm_xen_hypercall(vcpu);
-
- if (kvm_hv_hypercall_enabled(vcpu))
- return kvm_hv_hypercall(vcpu);
-
- nr = kvm_rax_read(vcpu);
- a0 = kvm_rbx_read(vcpu);
- a1 = kvm_rcx_read(vcpu);
- a2 = kvm_rdx_read(vcpu);
- a3 = kvm_rsi_read(vcpu);
+ unsigned long ret;

trace_kvm_hypercall(nr, a0, a1, a2, a3);

- op_64_bit = is_64_bit_hypercall(vcpu);
if (!op_64_bit) {
nr &= 0xFFFFFFFF;
a0 &= 0xFFFFFFFF;
@@ -10074,7 +10063,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
a3 &= 0xFFFFFFFF;
}

- if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
+ if (cpl) {
ret = -KVM_EPERM;
goto out;
}
@@ -10135,18 +10124,49 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)

WARN_ON_ONCE(vcpu->run->hypercall.flags & KVM_EXIT_HYPERCALL_MBZ);
vcpu->arch.complete_userspace_io = complete_hypercall_exit;
+ /* stat is incremented on completion. */
return 0;
}
default:
ret = -KVM_ENOSYS;
break;
}
+
out:
+ ++vcpu->stat.hypercalls;
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall);
+
+int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+{
+ unsigned long nr, a0, a1, a2, a3, ret;
+ int op_64_bit;
+ int cpl;
+
+ if (kvm_xen_hypercall_enabled(vcpu->kvm))
+ return kvm_xen_hypercall(vcpu);
+
+ if (kvm_hv_hypercall_enabled(vcpu))
+ return kvm_hv_hypercall(vcpu);
+
+ nr = kvm_rax_read(vcpu);
+ a0 = kvm_rbx_read(vcpu);
+ a1 = kvm_rcx_read(vcpu);
+ a2 = kvm_rdx_read(vcpu);
+ a3 = kvm_rsi_read(vcpu);
+ op_64_bit = is_64_bit_hypercall(vcpu);
+ cpl = static_call(kvm_x86_get_cpl)(vcpu);
+
+ ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl);
+ if (nr == KVM_HC_MAP_GPA_RANGE && !ret)
+ /* MAP_GPA tosses the request to the user space. */
+ return 0;
+
if (!op_64_bit)
ret = (u32)ret;
kvm_rax_write(vcpu, ret);

- ++vcpu->stat.hypercalls;
return kvm_skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);
--
2.39.0

2024-02-28 02:34:38

by Xiaoyao Li

[permalink] [raw]

Subject: Re: [PATCH 01/21] KVM: x86: Split core of hypercall emulation to helper function

2024-03-05 07:28:45

by Binbin Wu

[permalink] [raw]

Subject: Re: [PATCH 01/21] KVM: x86: Split core of hypercall emulation to helper function

On 2/28/2024 7:20 AM, Paolo Bonzini wrote:
> From: Sean Christopherson <[email protected]>
>
> By necessity, TDX will use a different register ABI for hypercalls.
> Break out the core functionality so that it may be reused for TDX.
>
> Signed-off-by: Sean Christopherson <[email protected]>
> Signed-off-by: Isaku Yamahata <[email protected]>
> Message-Id: <5134caa55ac3dec33fb2addb5545b52b3b52db02.1705965635.git.isaku.yamahata@intel.com>
> Signed-off-by: Paolo Bonzini <[email protected]>

Reviewed-by: Binbin Wu <[email protected]>

> ---
> arch/x86/include/asm/kvm_host.h | 4 +++
> arch/x86/kvm/x86.c | 56 ++++++++++++++++++++++-----------
> 2 files changed, 42 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 724a0c778f79..85dc0f7d09e3 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2133,6 +2133,10 @@ static inline void kvm_clear_apicv_inhibit(struct kvm *kvm,
> kvm_set_or_clear_apicv_inhibit(kvm, reason, false);
> }
>
> +unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
> + unsigned long a0, unsigned long a1,
> + unsigned long a2, unsigned long a3,
> + int op_64_bit, int cpl);
> int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
>
> int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b9dfe3179332..f10a5a617120 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10046,26 +10046,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu)
> return kvm_skip_emulated_instruction(vcpu);
> }
>
> -int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
> +unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
> + unsigned long a0, unsigned long a1,
> + unsigned long a2, unsigned long a3,
> + int op_64_bit, int cpl)
> {
> - unsigned long nr, a0, a1, a2, a3, ret;
> - int op_64_bit;
> -
> - if (kvm_xen_hypercall_enabled(vcpu->kvm))
> - return kvm_xen_hypercall(vcpu);
> -
> - if (kvm_hv_hypercall_enabled(vcpu))
> - return kvm_hv_hypercall(vcpu);
> -
> - nr = kvm_rax_read(vcpu);
> - a0 = kvm_rbx_read(vcpu);
> - a1 = kvm_rcx_read(vcpu);
> - a2 = kvm_rdx_read(vcpu);
> - a3 = kvm_rsi_read(vcpu);
> + unsigned long ret;
>
> trace_kvm_hypercall(nr, a0, a1, a2, a3);
>
> - op_64_bit = is_64_bit_hypercall(vcpu);
> if (!op_64_bit) {
> nr &= 0xFFFFFFFF;
> a0 &= 0xFFFFFFFF;
> @@ -10074,7 +10063,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
> a3 &= 0xFFFFFFFF;
> }
>
> - if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
> + if (cpl) {
> ret = -KVM_EPERM;
> goto out;
> }
> @@ -10135,18 +10124,49 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
>
> WARN_ON_ONCE(vcpu->run->hypercall.flags & KVM_EXIT_HYPERCALL_MBZ);
> vcpu->arch.complete_userspace_io = complete_hypercall_exit;
> + /* stat is incremented on completion. */
> return 0;
> }
> default:
> ret = -KVM_ENOSYS;
> break;
> }
> +
> out:
> + ++vcpu->stat.hypercalls;
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall);
> +
> +int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
> +{
> + unsigned long nr, a0, a1, a2, a3, ret;
> + int op_64_bit;
> + int cpl;
> +
> + if (kvm_xen_hypercall_enabled(vcpu->kvm))
> + return kvm_xen_hypercall(vcpu);
> +
> + if (kvm_hv_hypercall_enabled(vcpu))
> + return kvm_hv_hypercall(vcpu);
> +
> + nr = kvm_rax_read(vcpu);
> + a0 = kvm_rbx_read(vcpu);
> + a1 = kvm_rcx_read(vcpu);
> + a2 = kvm_rdx_read(vcpu);
> + a3 = kvm_rsi_read(vcpu);
> + op_64_bit = is_64_bit_hypercall(vcpu);
> + cpl = static_call(kvm_x86_get_cpl)(vcpu);
> +
> + ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit, cpl);
> + if (nr == KVM_HC_MAP_GPA_RANGE && !ret)
> + /* MAP_GPA tosses the request to the user space. */
> + return 0;
> +
> if (!op_64_bit)
> ret = (u32)ret;
> kvm_rax_write(vcpu, ret);
>
> - ++vcpu->stat.hypercalls;
> return kvm_skip_emulated_instruction(vcpu);
> }
> EXPORT_SYMBOL_GPL(kvm_emulate_hypercall);