linux-kernel - Re: [RFC, PATCH 02/12] x86/virt/tdx: Allocate reference counters for PAMT memory

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Message-ID: <mfimpdavswvvwot6kosmfgkg2grnbv4fkw3lsonytpcoiiso7v@n6e5mjxo4ewo>
Date: Mon, 12 May 2025 12:51:46 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Chao Gao <chao.gao@...el.com>
Cc: pbonzini@...hat.com, seanjc@...gle.com, rick.p.edgecombe@...el.com, 
	isaku.yamahata@...el.com, kai.huang@...el.com, yan.y.zhao@...el.com, tglx@...utronix.de, 
	mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com, kvm@...r.kernel.org, 
	x86@...nel.org, linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [RFC, PATCH 02/12] x86/virt/tdx: Allocate reference counters for
 PAMT memory

On Fri, May 09, 2025 at 05:52:16PM +0800, Chao Gao wrote:
> >+static int init_pamt_metadata(void)
> >+{
> >+	size_t size = max_pfn / PTRS_PER_PTE * sizeof(*pamt_refcounts);
> >+	struct vm_struct *area;
> >+
> >+	if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
> >+		return 0;
> >+
> >+	/*
> >+	 * Reserve vmalloc range for PAMT reference counters. It covers all
> >+	 * physical address space up to max_pfn. It is going to be populated
> >+	 * from init_tdmr() only for present memory that available for TDX use.
> >+	 */
> >+	area = get_vm_area(size, VM_IOREMAP);
> >+	if (!area)
> >+		return -ENOMEM;
> >+
> >+	pamt_refcounts = area->addr;
> >+	return 0;
> >+}
> >+
> >+static void free_pamt_metadata(void)
> >+{
> >+	size_t size = max_pfn / PTRS_PER_PTE * sizeof(*pamt_refcounts);
> >+
> 
> Shouldn't the free path also be gated by tdx_supports_dynamic_pamt()?

True. Missed this.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov