linux-kernel - Re: [RFC PATCH v5 20/45] KVM: x86/mmu: Allocate/free S-EPT pages using tdx_{alloc,free}_control

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Message-ID: <e81151ce-6e67-48e8-a722-da9ff03d686b@intel.com>
Date: Mon, 9 Feb 2026 15:40:13 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Sean Christopherson <seanjc@...gle.com>, Yan Zhao <yan.y.zhao@...el.com>
Cc: Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, Kiryl Shutsemau <kas@...nel.org>,
 Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
 linux-coco@...ts.linux.dev, kvm@...r.kernel.org,
 Kai Huang <kai.huang@...el.com>, Rick Edgecombe
 <rick.p.edgecombe@...el.com>, Vishal Annapurve <vannapurve@...gle.com>,
 Ackerley Tng <ackerleytng@...gle.com>, Sagi Shahar <sagis@...gle.com>,
 Binbin Wu <binbin.wu@...ux.intel.com>, Xiaoyao Li <xiaoyao.li@...el.com>,
 Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [RFC PATCH v5 20/45] KVM: x86/mmu: Allocate/free S-EPT pages
 using tdx_{alloc,free}_control_page()

On 2/6/26 07:01, Sean Christopherson wrote:
>  /* Bump PAMT refcount for the given page and allocate PAMT memory if needed */
>  int __tdx_pamt_get(u64 pfn, struct tdx_pamt_cache *cache)
> @@ -2272,7 +2272,7 @@ int __tdx_pamt_get(u64 pfn, struct tdx_pamt_cache *cache)
>         if (ret)
>                 goto out_free;
>  
> -       scoped_guard(spinlock, &pamt_lock) {
> +       scoped_guard(raw_spinlock_irqsave, &pamt_lock) {
>                 /*
>                  * Lost race to other tdx_pamt_add(). Other task has already allocated
>                  * PAMT memory for the HPA.
> @@ -2348,7 +2348,7 @@ void __tdx_pamt_put(u64 pfn)

Why does this need to be a raw spinlock? irqsave, sure, but raw?

The page allocator locks are used in this context and aren't raw.