linux-kernel - Re: [PATCH v5 17/32] x86/mm: Add support to access boot related data in the clear

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Date:   Sun, 21 May 2017 09:16:50 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     linux-arch@...r.kernel.org, linux-efi@...r.kernel.org,
        kvm@...r.kernel.org, linux-doc@...r.kernel.org, x86@...nel.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        iommu@...ts.linux-foundation.org, Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Larry Woodman <lwoodman@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dave Young <dyoung@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH v5 17/32] x86/mm: Add support to access boot related data
 in the clear

On Fri, May 19, 2017 at 03:50:32PM -0500, Tom Lendacky wrote:
> The "worker" function would be doing the loop through the setup data,
> but since the setup data is mapped inside the loop I can't do the __init
> calling the non-init function and still hope to consolidate the code.
> Maybe I'm missing something here...

Hmm, I see what you mean. But the below change ontop doesn't fire any
warnings here. Maybe your .config has something set which I don't...

---
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 55317ba3b6dc..199c983192ae 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -515,71 +515,50 @@ static bool memremap_is_efi_data(resource_size_t phys_addr,
  * Examine the physical address to determine if it is boot data by checking
  * it against the boot params setup_data chain.
  */
-static bool memremap_is_setup_data(resource_size_t phys_addr,
-				   unsigned long size)
+static bool
+__memremap_is_setup_data(resource_size_t phys_addr, unsigned long size, bool early)
 {
 	struct setup_data *data;
 	u64 paddr, paddr_next;
+	u32 len;
 
 	paddr = boot_params.hdr.setup_data;
 	while (paddr) {
-		bool is_setup_data = false;
 
 		if (phys_addr == paddr)
 			return true;
 
-		data = memremap(paddr, sizeof(*data),
-				MEMREMAP_WB | MEMREMAP_DEC);
+		if (early)
+			data = early_memremap_decrypted(paddr, sizeof(*data));
+		else
+			data = memremap(paddr, sizeof(*data), MEMREMAP_WB | MEMREMAP_DEC);
 
 		paddr_next = data->next;
+		len = data->len;
 
-		if ((phys_addr > paddr) && (phys_addr < (paddr + data->len)))
-			is_setup_data = true;
+		if (early)
+			early_memunmap(data, sizeof(*data));
+		else
+			memunmap(data);
 
-		memunmap(data);
 
-		if (is_setup_data)
+		if ((phys_addr > paddr) && (phys_addr < (paddr + data->len)))
 			return true;
 
 		paddr = paddr_next;
 	}
-
 	return false;
 }
 
-/*
- * Examine the physical address to determine if it is boot data by checking
- * it against the boot params setup_data chain (early boot version).
- */
 static bool __init early_memremap_is_setup_data(resource_size_t phys_addr,
 						unsigned long size)
 {
-	struct setup_data *data;
-	u64 paddr, paddr_next;
-
-	paddr = boot_params.hdr.setup_data;
-	while (paddr) {
-		bool is_setup_data = false;
-
-		if (phys_addr == paddr)
-			return true;
-
-		data = early_memremap_decrypted(paddr, sizeof(*data));
-
-		paddr_next = data->next;
-
-		if ((phys_addr > paddr) && (phys_addr < (paddr + data->len)))
-			is_setup_data = true;
-
-		early_memunmap(data, sizeof(*data));
-
-		if (is_setup_data)
-			return true;
-
-		paddr = paddr_next;
-	}
+	return __memremap_is_setup_data(phys_addr, size, true);
+}
 
-	return false;
+static bool memremap_is_setup_data(resource_size_t phys_addr, unsigned long size)
+{
+	return __memremap_is_setup_data(phys_addr, size, false);
 }
 
 /*

-- 
Regards/Gruss,
    Boris.

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