linux-kernel - Re: [PATCH v3 2/3] KVM: x86: Use kvzalloc() to allocate VM struct

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Message-ID: <aCyqs4VdPsw4mA_F@google.com>
Date: Tue, 20 May 2025 09:15:47 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Vipin Sharma <vipinsh@...gle.com>
Subject: Re: [PATCH v3 2/3] KVM: x86: Use kvzalloc() to allocate VM struct

On Fri, May 16, 2025, Sean Christopherson wrote:
> +/*
> + * Assert that "struct kvm_{svm,vmx,tdx}" is an order-0 or order-1 allocation.
> + * Spilling over to an order-2 allocation isn't fundamentally problematic, but
> + * isn't expected to happen in the foreseeable future (O(years)).  Assert that
> + * the size is an order-0 allocation when ignoring the memslot hash tables, to
> + * help detect and debug unexpected size increases.
> + */
> +#define KVM_SANITY_CHECK_VM_STRUCT_SIZE(x)						\
> +do {											\
> +	BUILD_BUG_ON(get_order(sizeof(struct x) - SIZE_OF_MEMSLOTS_HASHTABLE) &&	\
> +		     !IS_ENABLED(CONFIG_DEBUG_KERNEL) && !IS_ENABLED(CONFIG_KASAN));	\
> +	BUILD_BUG_ON(get_order(sizeof(struct x)) < 2 &&					\

Ugh, I jinxed myself.  My severe ineptitude and inability to test persists.  I
inverted this check, it should be:

		     get_order(sizeof(struct x)) >= 2

> +		     !IS_ENABLED(CONFIG_DEBUG_KERNEL) && !IS_ENABLED(CONFIG_KASAN));	\
> +} while (0)
> +
>  #define KVM_NESTED_VMENTER_CONSISTENCY_CHECK(consistency_check)		\
>  ({									\
>  	bool failed = (consistency_check);				\
> -- 
> 2.49.0.1112.g889b7c5bd8-goog
>