diff mbox series

[RFC,04/33] KVM: x86: hyper-v: Move hypercall page handling into separate function

Message ID 20231108111806.92604-5-nsaenz@amazon.com
State New
Headers
Series KVM: x86: hyperv: Introduce VSM support |

Commit Message

Nicolas Saenz Julienne Nov. 8, 2023, 11:17 a.m. UTC 
  The hypercall page patching is about to grow considerably, move it into
its own function.

No functional change intended.

Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
---
 arch/x86/kvm/hyperv.c | 69 ++++++++++++++++++++++++-------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

Comments

Maxim Levitsky Nov. 28, 2023, 7:01 a.m. UTC | #1 
On Wed, 2023-11-08 at 11:17 +0000, Nicolas Saenz Julienne wrote:
> The hypercall page patching is about to grow considerably, move it into
> its own function.
> 
> No functional change intended.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
> ---
>  arch/x86/kvm/hyperv.c | 69 ++++++++++++++++++++++++-------------------
>  1 file changed, 39 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index e1bc861ab3b0..78d053042667 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -256,6 +256,42 @@ static void synic_exit(struct kvm_vcpu_hv_synic *synic, u32 msr)
>  	kvm_make_request(KVM_REQ_HV_EXIT, vcpu);
>  }
>  
> +static int patch_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
> +{
> +	struct kvm *kvm = vcpu->kvm;
> +	u8 instructions[9];
> +	int i = 0;
> +	u64 addr;
> +
> +	/*
> +	 * If Xen and Hyper-V hypercalls are both enabled, disambiguate
> +	 * the same way Xen itself does, by setting the bit 31 of EAX
> +	 * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just
> +	 * going to be clobbered on 64-bit.
> +	 */
> +	if (kvm_xen_hypercall_enabled(kvm)) {
> +		/* orl $0x80000000, %eax */
> +		instructions[i++] = 0x0d;
> +		instructions[i++] = 0x00;
> +		instructions[i++] = 0x00;
> +		instructions[i++] = 0x00;
> +		instructions[i++] = 0x80;
> +	}
> +
> +	/* vmcall/vmmcall */
> +	static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i);
> +	i += 3;
> +
> +	/* ret */
> +	((unsigned char *)instructions)[i++] = 0xc3;
> +
> +	addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK;
> +	if (kvm_vcpu_write_guest(vcpu, addr, instructions, i))
> +		return 1;
> +
> +	return 0;
> +}
> +
>  static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
>  			 u32 msr, u64 data, bool host)
>  {
> @@ -1338,11 +1374,7 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
>  		if (!hv->hv_guest_os_id)
>  			hv->hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE;
>  		break;
> -	case HV_X64_MSR_HYPERCALL: {
> -		u8 instructions[9];
> -		int i = 0;
> -		u64 addr;
> -
> +	case HV_X64_MSR_HYPERCALL:
>  		/* if guest os id is not set hypercall should remain disabled */
>  		if (!hv->hv_guest_os_id)
>  			break;
> @@ -1351,34 +1383,11 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
>  			break;
>  		}
>  
> -		/*
> -		 * If Xen and Hyper-V hypercalls are both enabled, disambiguate
> -		 * the same way Xen itself does, by setting the bit 31 of EAX
> -		 * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just
> -		 * going to be clobbered on 64-bit.
> -		 */
> -		if (kvm_xen_hypercall_enabled(kvm)) {
> -			/* orl $0x80000000, %eax */
> -			instructions[i++] = 0x0d;
> -			instructions[i++] = 0x00;
> -			instructions[i++] = 0x00;
> -			instructions[i++] = 0x00;
> -			instructions[i++] = 0x80;
> -		}
> -
> -		/* vmcall/vmmcall */
> -		static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i);
> -		i += 3;
> -
> -		/* ret */
> -		((unsigned char *)instructions)[i++] = 0xc3;
> -
> -		addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK;
> -		if (kvm_vcpu_write_guest(vcpu, addr, instructions, i))
> +		if (patch_hypercall_page(vcpu, data))
>  			return 1;
> +
>  		hv->hv_hypercall = data;
>  		break;
> -	}
>  	case HV_X64_MSR_REFERENCE_TSC:
>  		hv->hv_tsc_page = data;
>  		if (hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) {


This looks like another nice cleanup that can be accepted to the kvm,
before the main VTL patch series.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
	Maxim Levitsky
diff mbox series

Patch

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index e1bc861ab3b0..78d053042667 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -256,6 +256,42 @@  static void synic_exit(struct kvm_vcpu_hv_synic *synic, u32 msr)
 	kvm_make_request(KVM_REQ_HV_EXIT, vcpu);
 }
 
+static int patch_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
+{
+	struct kvm *kvm = vcpu->kvm;
+	u8 instructions[9];
+	int i = 0;
+	u64 addr;
+
+	/*
+	 * If Xen and Hyper-V hypercalls are both enabled, disambiguate
+	 * the same way Xen itself does, by setting the bit 31 of EAX
+	 * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just
+	 * going to be clobbered on 64-bit.
+	 */
+	if (kvm_xen_hypercall_enabled(kvm)) {
+		/* orl $0x80000000, %eax */
+		instructions[i++] = 0x0d;
+		instructions[i++] = 0x00;
+		instructions[i++] = 0x00;
+		instructions[i++] = 0x00;
+		instructions[i++] = 0x80;
+	}
+
+	/* vmcall/vmmcall */
+	static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i);
+	i += 3;
+
+	/* ret */
+	((unsigned char *)instructions)[i++] = 0xc3;
+
+	addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK;
+	if (kvm_vcpu_write_guest(vcpu, addr, instructions, i))
+		return 1;
+
+	return 0;
+}
+
 static int synic_set_msr(struct kvm_vcpu_hv_synic *synic,
 			 u32 msr, u64 data, bool host)
 {
@@ -1338,11 +1374,7 @@  static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
 		if (!hv->hv_guest_os_id)
 			hv->hv_hypercall &= ~HV_X64_MSR_HYPERCALL_ENABLE;
 		break;
-	case HV_X64_MSR_HYPERCALL: {
-		u8 instructions[9];
-		int i = 0;
-		u64 addr;
-
+	case HV_X64_MSR_HYPERCALL:
 		/* if guest os id is not set hypercall should remain disabled */
 		if (!hv->hv_guest_os_id)
 			break;
@@ -1351,34 +1383,11 @@  static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
 			break;
 		}
 
-		/*
-		 * If Xen and Hyper-V hypercalls are both enabled, disambiguate
-		 * the same way Xen itself does, by setting the bit 31 of EAX
-		 * which is RsvdZ in the 32-bit Hyper-V hypercall ABI and just
-		 * going to be clobbered on 64-bit.
-		 */
-		if (kvm_xen_hypercall_enabled(kvm)) {
-			/* orl $0x80000000, %eax */
-			instructions[i++] = 0x0d;
-			instructions[i++] = 0x00;
-			instructions[i++] = 0x00;
-			instructions[i++] = 0x00;
-			instructions[i++] = 0x80;
-		}
-
-		/* vmcall/vmmcall */
-		static_call(kvm_x86_patch_hypercall)(vcpu, instructions + i);
-		i += 3;
-
-		/* ret */
-		((unsigned char *)instructions)[i++] = 0xc3;
-
-		addr = data & HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK;
-		if (kvm_vcpu_write_guest(vcpu, addr, instructions, i))
+		if (patch_hypercall_page(vcpu, data))
 			return 1;
+
 		hv->hv_hypercall = data;
 		break;
-	}
 	case HV_X64_MSR_REFERENCE_TSC:
 		hv->hv_tsc_page = data;
 		if (hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE) {