linux-kernel - Re: [PATCH v2 1/5] KVM: x86: Centralize KVM's VMware code

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Message-ID: <75aa80eeecb66050d80c2c6a793c6c20fab22a0f.camel@gmail.com>
Date: Tue, 22 Apr 2025 18:58:10 +0200
From: Francesco Lavra <francescolavra.fl@...il.com>
To: zack.rusin@...adcom.com
Cc: bp@...en8.de, dave.hansen@...ux.intel.com, doug.covelli@...adcom.com, 
 hpa@...or.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 mingo@...hat.com,  pbonzini@...hat.com, seanjc@...gle.com,
 tglx@...utronix.de, x86@...nel.org
Subject: Re: [PATCH v2 1/5] KVM: x86: Centralize KVM's VMware code

On 2025-04-22 at 16:12, Zack Rusin wrote:
> Centralize KVM's VMware specific code and introduce CONFIG_KVM_VMWARE
> to
> isolate all of it.
> 
> Code used to support VMware backdoor has been scattered around the
> KVM
> codebase making it difficult to reason about, maintain it and change
> it. Introduce CONFIG_KVM_VMWARE which, much like CONFIG_KVM_XEN and
> CONFIG_KVM_VMWARE for Xen and Hyper-V, abstracts away VMware specific

s/CONFIG_KVM_VMWARE/CONFIG_KVM_HYPERV/

> +static inline bool kvm_vmware_is_backdoor_opcode(u8 opcode_len, u8
> b)
> +{
> +	switch (opcode_len) {
> +	case 1:
> +		switch (b) {
> +		case 0xe4:	/* IN */
> +		case 0xe5:
> +		case 0xec:
> +		case 0xed:
> +		case 0xe6:	/* OUT */
> +		case 0xe7:
> +		case 0xee:
> +		case 0xef:
> +		case 0x6c:	/* INS */
> +		case 0x6d:
> +		case 0x6e:	/* OUTS */
> +		case 0x6f:
> +			return true;
> +		}
> +		break;
> +	case 2:
> +		switch (b) {
> +		case 0x33:	/* RDPMC */
> +			return true;
> +		}
> +		break;
> +	}
> +
> +	return false;
> +}
> +
> +#else /* !CONFIG_KVM_VMWARE */
> +
> +static inline bool kvm_vmware_backdoor_enabled(struct kvm_vcpu
> *vcpu)
> +{
> +	return false;
> +}
> +
> +static inline bool kvm_vmware_is_backdoor_pmc(u32 pmc_idx)
> +{
> +	return false;
> +}
> +
> +static inline bool kvm_vmware_io_port_allowed(u16 port)
> +{
> +	return false;
> +}
> +
> +static inline int kvm_vmware_pmu_rdpmc(struct kvm_vcpu *vcpu, u32
> idx, u64 *data)
> +{
> +	return 0;
> +}
> +
> +static inline bool kvm_vmware_is_backdoor_opcode(u8 opcode_len, u8
> len)

Nit: even though this is just a dummy function, its second parameter
`len` appears misnamed and for consistency should be named the same as
in the CONFIG_KVM_VMWARE function, i.e. `b`.