linux-kernel - Re: [PATCHv2 04/12] x86/virt/tdx: Add tdx_alloc/free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <g5akv7uwsdrvs3j4wsj2xmc3fpdlyudj5sjuhw62m3f4yjsxse@nrne5miazbx4>
Date: Fri, 27 Jun 2025 16:03:56 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: pbonzini@...hat.com, seanjc@...gle.com, dave.hansen@...ux.intel.com, 
	rick.p.edgecombe@...el.com, isaku.yamahata@...el.com, kai.huang@...el.com, 
	yan.y.zhao@...el.com, chao.gao@...el.com, tglx@...utronix.de, mingo@...hat.com, 
	bp@...en8.de, kvm@...r.kernel.org, x86@...nel.org, linux-coco@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 04/12] x86/virt/tdx: Add tdx_alloc/free_page() helpers

On Fri, Jun 27, 2025 at 10:49:34AM +0300, Adrian Hunter wrote:
> On 09/06/2025 22:13, Kirill A. Shutemov wrote:
> > +static void tdx_pamt_put(struct page *page, enum pg_level level)
> > +{
> > +	unsigned long hpa = page_to_phys(page);
> > +	atomic_t *pamt_refcount;
> > +	LIST_HEAD(pamt_pages);
> > +	u64 err;
> > +
> > +	if (!tdx_supports_dynamic_pamt(&tdx_sysinfo))
> > +		return;
> > +
> > +	if (level != PG_LEVEL_4K)
> > +		return;
> > +
> > +	hpa = ALIGN_DOWN(hpa, PMD_SIZE);
> > +
> > +	pamt_refcount = tdx_get_pamt_refcount(hpa);
> > +	if (!atomic_dec_and_test(pamt_refcount))
> > +		return;
> > +
> > +	scoped_guard(spinlock, &pamt_lock) {
> > +		/* Lost race against tdx_pamt_add()? */
> > +		if (atomic_read(pamt_refcount) != 0)
> > +			return;
> > +
> > +		err = tdh_phymem_pamt_remove(hpa | TDX_PS_2M, &pamt_pages);
> > +
> > +		if (err) {
> > +			atomic_inc(pamt_refcount);
> > +			pr_err("TDH_PHYMEM_PAMT_REMOVE failed: %#llx\n", err);
> > +			return;
> > +		}
> > +	}
> > +
> 
> Won't any pages that have been used need to be cleared
> before being freed.

Good point. I missed that.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov