[PATCH v8 20/38] x86, mpparse: Use memremap to map the mpf and mpc data

[Tom Lendacky]

The SMP MP-table is built by UEFI and placed in memory in a decrypted
state. These tables are accessed using a mix of early_memremap(),
early_memunmap(), phys_to_virt() and virt_to_phys(). Change all accesses
to use early_memremap()/early_memunmap(). This allows for proper setting
of the encryption mask so that the data can be successfully accessed when
SME is active.

Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 arch/x86/kernel/mpparse.c |   98 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 70 insertions(+), 28 deletions(-)

diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c
index fd37f39..5cbb317 100644
--- a/arch/x86/kernel/mpparse.c
+++ b/arch/x86/kernel/mpparse.c
@@ -429,7 +429,7 @@ static inline void __init construct_default_ISA_mptable(int mpc_default_type)
 	}
 }
 
-static struct mpf_intel *mpf_found;
+static unsigned long mpf_base;
 
 static unsigned long __init get_mpc_size(unsigned long physptr)
 {
@@ -451,6 +451,7 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early)
 
 	size = get_mpc_size(mpf->physptr);
 	mpc = early_memremap(mpf->physptr, size);
+
 	/*
 	 * Read the physical hardware table.  Anything here will
 	 * override the defaults.
@@ -497,12 +498,12 @@ static int __init check_physptr(struct mpf_intel *mpf, unsigned int early)
  */
 void __init default_get_smp_config(unsigned int early)
 {
-	struct mpf_intel *mpf = mpf_found;
+	struct mpf_intel *mpf;
 
 	if (!smp_found_config)
 		return;
 
-	if (!mpf)
+	if (!mpf_base)
 		return;
 
 	if (acpi_lapic && early)
@@ -515,6 +516,12 @@ void __init default_get_smp_config(unsigned int early)
 	if (acpi_lapic && acpi_ioapic)
 		return;
 
+	mpf = early_memremap(mpf_base, sizeof(*mpf));
+	if (!mpf) {
+		pr_err("MPTABLE: error mapping MP table\n");
+		return;
+	}
+
 	pr_info("Intel MultiProcessor Specification v1.%d\n",
 		mpf->specification);
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
@@ -529,7 +536,7 @@ void __init default_get_smp_config(unsigned int early)
 	/*
 	 * Now see if we need to read further.
 	 */
-	if (mpf->feature1 != 0) {
+	if (mpf->feature1) {
 		if (early) {
 			/*
 			 * local APIC has default address
@@ -542,8 +549,10 @@ void __init default_get_smp_config(unsigned int early)
 		construct_default_ISA_mptable(mpf->feature1);
 
 	} else if (mpf->physptr) {
-		if (check_physptr(mpf, early))
+		if (check_physptr(mpf, early)) {
+			early_memunmap(mpf, sizeof(*mpf));
 			return;
+		}
 	} else
 		BUG();
 
@@ -552,6 +561,8 @@ void __init default_get_smp_config(unsigned int early)
 	/*
 	 * Only use the first configuration found.
 	 */
+
+	early_memunmap(mpf, sizeof(*mpf));
 }
 
 static void __init smp_reserve_memory(struct mpf_intel *mpf)
@@ -561,15 +572,16 @@ static void __init smp_reserve_memory(struct mpf_intel *mpf)
 
 static int __init smp_scan_config(unsigned long base, unsigned long length)
 {
-	unsigned int *bp = phys_to_virt(base);
+	unsigned int *bp;
 	struct mpf_intel *mpf;
-	unsigned long mem;
+	int ret = 0;
 
 	apic_printk(APIC_VERBOSE, "Scan for SMP in [mem %#010lx-%#010lx]\n",
 		    base, base + length - 1);
 	BUILD_BUG_ON(sizeof(*mpf) != 16);
 
 	while (length > 0) {
+		bp = early_memremap(base, length);
 		mpf = (struct mpf_intel *)bp;
 		if ((*bp == SMP_MAGIC_IDENT) &&
 		    (mpf->length == 1) &&
@@ -579,24 +591,26 @@ static int __init smp_scan_config(unsigned long base, unsigned long length)
 #ifdef CONFIG_X86_LOCAL_APIC
 			smp_found_config = 1;
 #endif
-			mpf_found = mpf;
+			mpf_base = base;
 
-			pr_info("found SMP MP-table at [mem %#010llx-%#010llx] mapped at [%p]\n",
-				(unsigned long long) virt_to_phys(mpf),
-				(unsigned long long) virt_to_phys(mpf) +
-				sizeof(*mpf) - 1, mpf);
+			pr_info("found SMP MP-table at [mem %#010lx-%#010lx] mapped at [%p]\n",
+				base, base + sizeof(*mpf) - 1, mpf);
 
-			mem = virt_to_phys(mpf);
-			memblock_reserve(mem, sizeof(*mpf));
+			memblock_reserve(base, sizeof(*mpf));
 			if (mpf->physptr)
 				smp_reserve_memory(mpf);
 
-			return 1;
+			ret = 1;
 		}
-		bp += 4;
+		early_memunmap(bp, length);
+
+		if (ret)
+			break;
+
+		base += 16;
 		length -= 16;
 	}
-	return 0;
+	return ret;
 }
 
 void __init default_find_smp_config(void)
@@ -838,29 +852,40 @@ static int __init update_mp_table(void)
 	char oem[10];
 	struct mpf_intel *mpf;
 	struct mpc_table *mpc, *mpc_new;
+	unsigned long size;
 
 	if (!enable_update_mptable)
 		return 0;
 
-	mpf = mpf_found;
-	if (!mpf)
+	if (!mpf_base)
+		return 0;
+
+	mpf = early_memremap(mpf_base, sizeof(*mpf));
+	if (!mpf) {
+		pr_err("MPTABLE: mpf early_memremap() failed\n");
 		return 0;
+	}
 
 	/*
 	 * Now see if we need to go further.
 	 */
-	if (mpf->feature1 != 0)
-		return 0;
+	if (mpf->feature1)
+		goto do_unmap_mpf;
 
 	if (!mpf->physptr)
-		return 0;
+		goto do_unmap_mpf;
 
-	mpc = phys_to_virt(mpf->physptr);
+	size = get_mpc_size(mpf->physptr);
+	mpc = early_memremap(mpf->physptr, size);
+	if (!mpc) {
+		pr_err("MPTABLE: mpc early_memremap() failed\n");
+		goto do_unmap_mpf;
+	}
 
 	if (!smp_check_mpc(mpc, oem, str))
-		return 0;
+		goto do_unmap_mpc;
 
-	pr_info("mpf: %llx\n", (u64)virt_to_phys(mpf));
+	pr_info("mpf: %llx\n", (u64)mpf_base);
 	pr_info("physptr: %x\n", mpf->physptr);
 
 	if (mpc_new_phys && mpc->length > mpc_new_length) {
@@ -878,21 +903,32 @@ static int __init update_mp_table(void)
 		new = mpf_checksum((unsigned char *)mpc, mpc->length);
 		if (old == new) {
 			pr_info("mpc is readonly, please try alloc_mptable instead\n");
-			return 0;
+			goto do_unmap_mpc;
 		}
 		pr_info("use in-position replacing\n");
 	} else {
+		mpc_new = early_memremap(mpc_new_phys, mpc_new_length);
+		if (!mpc_new) {
+			pr_err("MPTABLE: new mpc early_memremap() failed\n");
+			goto do_unmap_mpc;
+		}
 		mpf->physptr = mpc_new_phys;
-		mpc_new = phys_to_virt(mpc_new_phys);
 		memcpy(mpc_new, mpc, mpc->length);
+		early_memunmap(mpc, size);
 		mpc = mpc_new;
+		size = mpc_new_length;
 		/* check if we can modify that */
 		if (mpc_new_phys - mpf->physptr) {
 			struct mpf_intel *mpf_new;
 			/* steal 16 bytes from [0, 1k) */
+			mpf_new = early_memremap(0x400 - 16, sizeof(*mpf_new));
+			if (!mpf_new) {
+				pr_err("MPTABLE: new mpf early_memremap() failed\n");
+				goto do_unmap_mpc;
+			}
 			pr_info("mpf new: %x\n", 0x400 - 16);
-			mpf_new = phys_to_virt(0x400 - 16);
 			memcpy(mpf_new, mpf, 16);
+			early_memunmap(mpf, sizeof(*mpf));
 			mpf = mpf_new;
 			mpf->physptr = mpc_new_phys;
 		}
@@ -909,6 +945,12 @@ static int __init update_mp_table(void)
 	 */
 	replace_intsrc_all(mpc, mpc_new_phys, mpc_new_length);
 
+do_unmap_mpc:
+	early_memunmap(mpc, size);
+
+do_unmap_mpf:
+	early_memunmap(mpf, sizeof(*mpf));
+
 	return 0;
 }