linux-kernel - Re: [PATCH] x86/sev: Fix host kdump support for SNP

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Message-ID: <CABgObfZMQ1qcQf-XLZaPGFzmbtoe3gGuMvXF-N0qo_5Z9jf+vg@mail.gmail.com>
Date: Mon, 2 Sep 2024 17:05:08 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Ashish Kalra <Ashish.Kalra@....com>
Cc: seanjc@...gle.com, dave.hansen@...ux.intel.com, tglx@...utronix.de, 
	mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com, 
	peterz@...radead.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
	thomas.lendacky@....com, michael.roth@....com, kexec@...ts.infradead.org, 
	linux-coco@...ts.linux.dev
Subject: Re: [PATCH] x86/sev: Fix host kdump support for SNP

On Tue, Aug 27, 2024 at 10:40 PM Ashish Kalra <Ashish.Kalra@....com> wrote:
> +void snp_decommision_all(void)

Should be spelled snp_decommission_all (with two "s").

> +static DEFINE_SPINLOCK(snp_decommision_lock);

Same here.

>  /*
>   * Only MSR_TSC_AUX is switched via the user return hook.  EFER is switched via
>   * the VMCB, and the SYSCALL/SYSENTER MSRs are handled by VMLOAD/VMSAVE.
> @@ -594,9 +597,97 @@ static inline void kvm_cpu_svm_disable(void)
>
>  static void svm_emergency_disable(void)
>  {
> +       static atomic_t waiting_for_cpus_synchronized;
> +       static bool synchronize_cpus_initiated;
> +       static bool snp_decommision_handled;

Same here, and below throughout the function (also SNP_DECOMMISSION).

Please create a new function sev_emergency_disable(), with a stub in
svm.h if CONFIG_KVM_AMD_

> @@ -749,6 +749,7 @@ void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu);
>  int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order);
>  void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end);
>  int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn);
> +void snp_decommision_all(void);
>  #else
>  static inline struct page *snp_safe_alloc_page_node(int node, gfp_t gfp)
>  {
> @@ -779,7 +780,7 @@ static inline int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn)
>  {
>         return 0;
>  }
> -
> +static void snp_decommision_all(void);

This should be inline (and after the change above it should be
sev_emergency_disable(), not snp_decommission_all(), that is exported
from sev.c).

Thanks,

Paolo