A set of x86 fixes and updates:

- Make the prctl() for enabling dynamic XSTATE components correct so it
     adds the newly requested feature to the permission bitmap instead of
     overwriting it. Add a selftest which validates that.
 
   - Unroll string MMIO for encrypted SEV guests as the hypervisor cannot
     emulate it.
 
   - Handle supervisor states correctly in the FPU/XSTATE code so it takes
     the feature set of the fpstate buffer into account. The feature sets
     can differ between host and guest buffers. Guest buffers do not contain
     supervisor states. So far this was not an issue, but with enabling
     PASID it needs to be handled in the buffer offset calculation and in
     the permission bitmaps.
 
   - Avoid a gazillion of repeated CPUID invocations in by caching the values
     early in the FPU/XSTATE code.
 
   - Enable CONFIG_WERROR for X86.
 
   - Make the X86 defconfigs more useful by adapting them to Y2022 reality.
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Merge tag 'x86-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:
 "A set of x86 fixes and updates:

   - Make the prctl() for enabling dynamic XSTATE components correct so
     it adds the newly requested feature to the permission bitmap
     instead of overwriting it. Add a selftest which validates that.

   - Unroll string MMIO for encrypted SEV guests as the hypervisor
     cannot emulate it.

   - Handle supervisor states correctly in the FPU/XSTATE code so it
     takes the feature set of the fpstate buffer into account. The
     feature sets can differ between host and guest buffers. Guest
     buffers do not contain supervisor states. So far this was not an
     issue, but with enabling PASID it needs to be handled in the buffer
     offset calculation and in the permission bitmaps.

   - Avoid a gazillion of repeated CPUID invocations in by caching the
     values early in the FPU/XSTATE code.

   - Enable CONFIG_WERROR in x86 defconfig.

   - Make the X86 defconfigs more useful by adapting them to Y2022
     reality"

* tag 'x86-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu/xstate: Consolidate size calculations
  x86/fpu/xstate: Handle supervisor states in XSTATE permissions
  x86/fpu/xsave: Handle compacted offsets correctly with supervisor states
  x86/fpu: Cache xfeature flags from CPUID
  x86/fpu/xsave: Initialize offset/size cache early
  x86/fpu: Remove unused supervisor only offsets
  x86/fpu: Remove redundant XCOMP_BV initialization
  x86/sev: Unroll string mmio with CC_ATTR_GUEST_UNROLL_STRING_IO
  x86/config: Make the x86 defconfigs a bit more usable
  x86/defconfig: Enable WERROR
  selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test
  x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation

arch/x86/configs/i386_defconfig

@@ -1,5 +1,7 @@
+CONFIG_WERROR=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
+CONFIG_USELIB=y
 CONFIG_AUDIT=y
 CONFIG_NO_HZ=y
 CONFIG_HIGH_RES_TIMERS=y
@@ -11,23 +13,30 @@ CONFIG_TASK_XACCT=y
 CONFIG_TASK_IO_ACCOUNTING=y
 CONFIG_LOG_BUF_SHIFT=18
 CONFIG_CGROUPS=y
+CONFIG_BLK_CGROUP=y
 CONFIG_CGROUP_SCHED=y
+CONFIG_CGROUP_PIDS=y
+CONFIG_CGROUP_RDMA=y
 CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_HUGETLB=y
 CONFIG_CPUSETS=y
+CONFIG_CGROUP_DEVICE=y
 CONFIG_CGROUP_CPUACCT=y
+CONFIG_CGROUP_PERF=y
+CONFIG_CGROUP_MISC=y
+CONFIG_CGROUP_DEBUG=y
 CONFIG_BLK_DEV_INITRD=y
+CONFIG_KALLSYMS_ALL=y
 # CONFIG_COMPAT_BRK is not set
 CONFIG_PROFILING=y
-# CONFIG_64BIT is not set
 CONFIG_SMP=y
-CONFIG_X86_GENERIC=y
+CONFIG_HYPERVISOR_GUEST=y
-CONFIG_HPET_TIMER=y
+CONFIG_PARAVIRT=y
+CONFIG_NR_CPUS=8
 CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS=y
-CONFIG_X86_REBOOTFIXUPS=y
 CONFIG_MICROCODE_AMD=y
 CONFIG_X86_MSR=y
 CONFIG_X86_CPUID=y
-CONFIG_HIGHPTE=y
 CONFIG_X86_CHECK_BIOS_CORRUPTION=y
 # CONFIG_MTRR_SANITIZER is not set
 CONFIG_EFI=y
@@ -43,12 +52,15 @@ CONFIG_ACPI_BGRT=y
 CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y
 CONFIG_CPU_FREQ_GOV_ONDEMAND=y
 CONFIG_X86_ACPI_CPUFREQ=y
-CONFIG_EFI_VARS=y
 CONFIG_KPROBES=y
 CONFIG_JUMP_LABEL=y
+CONFIG_COMPAT_32BIT_TIME=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
 CONFIG_MODULE_FORCE_UNLOAD=y
+CONFIG_BLK_CGROUP_IOLATENCY=y
+CONFIG_BLK_CGROUP_IOCOST=y
+CONFIG_BLK_CGROUP_IOPRIO=y
 CONFIG_BINFMT_MISC=y
 CONFIG_NET=y
 CONFIG_PACKET=y
@@ -103,12 +115,16 @@ CONFIG_IP6_NF_FILTER=y
 CONFIG_IP6_NF_TARGET_REJECT=y
 CONFIG_IP6_NF_MANGLE=y
 CONFIG_NET_SCHED=y
+CONFIG_NET_CLS_CGROUP=y
 CONFIG_NET_EMATCH=y
 CONFIG_NET_CLS_ACT=y
+CONFIG_CGROUP_NET_PRIO=y
 CONFIG_CFG80211=y
 CONFIG_MAC80211=y
 CONFIG_MAC80211_LEDS=y
 CONFIG_RFKILL=y
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
 CONFIG_PCI=y
 CONFIG_PCIEPORTBUS=y
 CONFIG_PCI_MSI=y
@@ -119,13 +135,16 @@ CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DEBUG_DEVRES=y
 CONFIG_CONNECTOR=y
+CONFIG_EFI_VARS=y
+CONFIG_EFI_CAPSULE_LOADER=y
 CONFIG_BLK_DEV_LOOP=y
+CONFIG_VIRTIO_BLK=y
 CONFIG_BLK_DEV_SD=y
 CONFIG_BLK_DEV_SR=y
 CONFIG_CHR_DEV_SG=y
 CONFIG_SCSI_CONSTANTS=y
 CONFIG_SCSI_SPI_ATTRS=y
-# CONFIG_SCSI_LOWLEVEL is not set
+CONFIG_SCSI_VIRTIO=y
 CONFIG_ATA=y
 CONFIG_SATA_AHCI=y
 CONFIG_ATA_PIIX=y
@@ -143,6 +162,7 @@ CONFIG_MACINTOSH_DRIVERS=y
 CONFIG_MAC_EMUMOUSEBTN=y
 CONFIG_NETDEVICES=y
 CONFIG_NETCONSOLE=y
+CONFIG_VIRTIO_NET=y
 CONFIG_BNX2=y
 CONFIG_TIGON3=y
 CONFIG_NET_TULIP=y
@@ -170,6 +190,7 @@ CONFIG_SERIAL_8250_SHARE_IRQ=y
 CONFIG_SERIAL_8250_DETECT_IRQ=y
 CONFIG_SERIAL_8250_RSA=y
 CONFIG_SERIAL_NONSTANDARD=y
+CONFIG_VIRTIO_CONSOLE=y
 CONFIG_HW_RANDOM=y
 CONFIG_NVRAM=y
 CONFIG_HPET=y
@@ -181,12 +202,7 @@ CONFIG_AGP_AMD64=y
 CONFIG_AGP_INTEL=y
 CONFIG_DRM=y
 CONFIG_DRM_I915=y
-CONFIG_FB_MODE_HELPERS=y
+CONFIG_DRM_VIRTIO_GPU=y
-CONFIG_FB_TILEBLITTING=y
-CONFIG_FB_EFI=y
-CONFIG_LOGO=y
-# CONFIG_LOGO_LINUX_MONO is not set
-# CONFIG_LOGO_LINUX_VGA16 is not set
 CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_HRTIMER=y
@@ -219,6 +235,8 @@ CONFIG_USB_STORAGE=y
 CONFIG_RTC_CLASS=y
 # CONFIG_RTC_HCTOSYS is not set
 CONFIG_DMADEVICES=y
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_INPUT=y
 CONFIG_EEEPC_LAPTOP=y
 CONFIG_EXT4_FS=y
 CONFIG_EXT4_FS_POSIX_ACL=y
@@ -240,6 +258,7 @@ CONFIG_NFS_FS=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
+CONFIG_9P_FS=y
 CONFIG_NLS_DEFAULT="utf8"
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
@@ -251,14 +270,15 @@ CONFIG_SECURITY_SELINUX=y
 CONFIG_SECURITY_SELINUX_BOOTPARAM=y
 CONFIG_SECURITY_SELINUX_DISABLE=y
 CONFIG_PRINTK_TIME=y
+CONFIG_FRAME_WARN=1024
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_STACK_USAGE=y
-CONFIG_DEBUG_STACKOVERFLOW=y
 # CONFIG_SCHED_DEBUG is not set
 CONFIG_SCHEDSTATS=y
 CONFIG_BLK_DEV_IO_TRACE=y
 CONFIG_PROVIDE_OHCI1394_DMA_INIT=y
 CONFIG_EARLY_PRINTK_DBGP=y
 CONFIG_DEBUG_BOOT_PARAMS=y
-CONFIG_KALLSYMS_ALL=y
+CONFIG_UNWINDER_FRAME_POINTER=y
+# CONFIG_64BIT is not set

arch/x86/configs/x86_64_defconfig

@@ -1,3 +1,4 @@
+CONFIG_WERROR=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
 CONFIG_AUDIT=y
@@ -11,14 +12,25 @@ CONFIG_TASK_XACCT=y
 CONFIG_TASK_IO_ACCOUNTING=y
 CONFIG_LOG_BUF_SHIFT=18
 CONFIG_CGROUPS=y
+CONFIG_BLK_CGROUP=y
 CONFIG_CGROUP_SCHED=y
+CONFIG_CGROUP_PIDS=y
+CONFIG_CGROUP_RDMA=y
 CONFIG_CGROUP_FREEZER=y
+CONFIG_CGROUP_HUGETLB=y
 CONFIG_CPUSETS=y
+CONFIG_CGROUP_DEVICE=y
 CONFIG_CGROUP_CPUACCT=y
+CONFIG_CGROUP_PERF=y
+CONFIG_CGROUP_MISC=y
+CONFIG_CGROUP_DEBUG=y
 CONFIG_BLK_DEV_INITRD=y
+CONFIG_KALLSYMS_ALL=y
 # CONFIG_COMPAT_BRK is not set
 CONFIG_PROFILING=y
 CONFIG_SMP=y
+CONFIG_HYPERVISOR_GUEST=y
+CONFIG_PARAVIRT=y
 CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS=y
 CONFIG_MICROCODE_AMD=y
 CONFIG_X86_MSR=y
@@ -41,12 +53,14 @@ CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y
 CONFIG_CPU_FREQ_GOV_ONDEMAND=y
 CONFIG_X86_ACPI_CPUFREQ=y
 CONFIG_IA32_EMULATION=y
-CONFIG_EFI_VARS=y
 CONFIG_KPROBES=y
 CONFIG_JUMP_LABEL=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
 CONFIG_MODULE_FORCE_UNLOAD=y
+CONFIG_BLK_CGROUP_IOLATENCY=y
+CONFIG_BLK_CGROUP_IOCOST=y
+CONFIG_BLK_CGROUP_IOPRIO=y
 CONFIG_BINFMT_MISC=y
 CONFIG_NET=y
 CONFIG_PACKET=y
@@ -101,12 +115,16 @@ CONFIG_IP6_NF_FILTER=y
 CONFIG_IP6_NF_TARGET_REJECT=y
 CONFIG_IP6_NF_MANGLE=y
 CONFIG_NET_SCHED=y
+CONFIG_NET_CLS_CGROUP=y
 CONFIG_NET_EMATCH=y
 CONFIG_NET_CLS_ACT=y
+CONFIG_CGROUP_NET_PRIO=y
 CONFIG_CFG80211=y
 CONFIG_MAC80211=y
 CONFIG_MAC80211_LEDS=y
 CONFIG_RFKILL=y
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
 CONFIG_PCI=y
 CONFIG_PCIEPORTBUS=y
 CONFIG_HOTPLUG_PCI=y
@@ -116,13 +134,15 @@ CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_DEBUG_DEVRES=y
 CONFIG_CONNECTOR=y
+CONFIG_EFI_VARS=y
 CONFIG_BLK_DEV_LOOP=y
+CONFIG_VIRTIO_BLK=y
 CONFIG_BLK_DEV_SD=y
 CONFIG_BLK_DEV_SR=y
 CONFIG_CHR_DEV_SG=y
 CONFIG_SCSI_CONSTANTS=y
 CONFIG_SCSI_SPI_ATTRS=y
-# CONFIG_SCSI_LOWLEVEL is not set
+CONFIG_SCSI_VIRTIO=y
 CONFIG_ATA=y
 CONFIG_SATA_AHCI=y
 CONFIG_ATA_PIIX=y
@@ -138,6 +158,7 @@ CONFIG_MACINTOSH_DRIVERS=y
 CONFIG_MAC_EMUMOUSEBTN=y
 CONFIG_NETDEVICES=y
 CONFIG_NETCONSOLE=y
+CONFIG_VIRTIO_NET=y
 CONFIG_TIGON3=y
 CONFIG_NET_TULIP=y
 CONFIG_E100=y
@@ -162,6 +183,7 @@ CONFIG_SERIAL_8250_SHARE_IRQ=y
 CONFIG_SERIAL_8250_DETECT_IRQ=y
 CONFIG_SERIAL_8250_RSA=y
 CONFIG_SERIAL_NONSTANDARD=y
+CONFIG_VIRTIO_CONSOLE=y
 CONFIG_HW_RANDOM=y
 # CONFIG_HW_RANDOM_INTEL is not set
 # CONFIG_HW_RANDOM_AMD is not set
@@ -175,12 +197,7 @@ CONFIG_AGP_AMD64=y
 CONFIG_AGP_INTEL=y
 CONFIG_DRM=y
 CONFIG_DRM_I915=y
-CONFIG_FB_MODE_HELPERS=y
+CONFIG_DRM_VIRTIO_GPU=y
-CONFIG_FB_TILEBLITTING=y
-CONFIG_FB_EFI=y
-CONFIG_LOGO=y
-# CONFIG_LOGO_LINUX_MONO is not set
-# CONFIG_LOGO_LINUX_VGA16 is not set
 CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_HRTIMER=y
@@ -213,6 +230,8 @@ CONFIG_USB_STORAGE=y
 CONFIG_RTC_CLASS=y
 # CONFIG_RTC_HCTOSYS is not set
 CONFIG_DMADEVICES=y
+CONFIG_VIRTIO_PCI=y
+CONFIG_VIRTIO_INPUT=y
 CONFIG_EEEPC_LAPTOP=y
 CONFIG_AMD_IOMMU=y
 CONFIG_INTEL_IOMMU=y
@@ -237,6 +256,7 @@ CONFIG_NFS_FS=y
 CONFIG_NFS_V3_ACL=y
 CONFIG_NFS_V4=y
 CONFIG_ROOT_NFS=y
+CONFIG_9P_FS=y
 CONFIG_NLS_DEFAULT="utf8"
 CONFIG_NLS_CODEPAGE_437=y
 CONFIG_NLS_ASCII=y
@@ -257,4 +277,3 @@ CONFIG_BLK_DEV_IO_TRACE=y
 CONFIG_PROVIDE_OHCI1394_DMA_INIT=y
 CONFIG_EARLY_PRINTK_DBGP=y
 CONFIG_DEBUG_BOOT_PARAMS=y
-CONFIG_KALLSYMS_ALL=y

arch/x86/kernel/fpu/core.c

@@ -415,9 +415,6 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf,
 		xpkru = get_xsave_addr(&kstate->regs.xsave, XFEATURE_PKRU);
 		*vpkru = xpkru->pkru;
 	}
-
-	/* Ensure that XCOMP_BV is set up for XSAVES */
-	xstate_init_xcomp_bv(&kstate->regs.xsave, kstate->xfeatures);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(fpu_copy_uabi_to_guest_fpstate);

arch/x86/kernel/fpu/xstate.c

@@ -81,10 +81,10 @@ static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init =
 	{ [ 0 ... XFEATURE_MAX - 1] = -1};
 static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init =
 	{ [ 0 ... XFEATURE_MAX - 1] = -1};
-static unsigned int xstate_comp_offsets[XFEATURE_MAX] __ro_after_init =
+static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init;
-	{ [ 0 ... XFEATURE_MAX - 1] = -1};
+
-static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] __ro_after_init =
+#define XSTATE_FLAG_SUPERVISOR	BIT(0)
-	{ [ 0 ... XFEATURE_MAX - 1] = -1};
+#define XSTATE_FLAG_ALIGNED64	BIT(1)
 
 /*
  * Return whether the system supports a given xfeature.
@@ -124,17 +124,41 @@ int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name)
 }
 EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
 
+static bool xfeature_is_aligned64(int xfeature_nr)
+{
+	return xstate_flags[xfeature_nr] & XSTATE_FLAG_ALIGNED64;
+}
+
 static bool xfeature_is_supervisor(int xfeature_nr)
 {
-	/*
+	return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR;
-	 * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1)
+}
-	 * returns ECX[0] set to (1) for a supervisor state, and cleared (0)
-	 * for a user state.
-	 */
-	u32 eax, ebx, ecx, edx;
 
-	cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
+static unsigned int xfeature_get_offset(u64 xcomp_bv, int xfeature)
-	return ecx & 1;
+{
+	unsigned int offs, i;
+
+	/*
+	 * Non-compacted format and legacy features use the cached fixed
+	 * offsets.
+	 */
+	if (!cpu_feature_enabled(X86_FEATURE_XSAVES) || xfeature <= XFEATURE_SSE)
+		return xstate_offsets[xfeature];
+
+	/*
+	 * Compacted format offsets depend on the actual content of the
+	 * compacted xsave area which is determined by the xcomp_bv header
+	 * field.
+	 */
+	offs = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	for_each_extended_xfeature(i, xcomp_bv) {
+		if (xfeature_is_aligned64(i))
+			offs = ALIGN(offs, 64);
+		if (i == xfeature)
+			break;
+		offs += xstate_sizes[i];
+	}
+	return offs;
 }
 
 /*
@@ -182,7 +206,7 @@ static bool xfeature_enabled(enum xfeature xfeature)
  * Record the offsets and sizes of various xstates contained
  * in the XSAVE state memory layout.
  */
-static void __init setup_xstate_features(void)
+static void __init setup_xstate_cache(void)
 {
 	u32 eax, ebx, ecx, edx, i;
 	/* start at the beginning of the "extended state" */
@@ -205,6 +229,7 @@ static void __init setup_xstate_features(void)
 		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
 
 		xstate_sizes[i] = eax;
+		xstate_flags[i] = ecx;
 
 		/*
 		 * If an xfeature is supervisor state, the offset in EBX is
@@ -263,94 +288,6 @@ static void __init print_xstate_features(void)
 	WARN_ON(nr >= XFEATURE_MAX);	\
 } while (0)
 
-/*
- * We could cache this like xstate_size[], but we only use
- * it here, so it would be a waste of space.
- */
-static int xfeature_is_aligned(int xfeature_nr)
-{
-	u32 eax, ebx, ecx, edx;
-
-	CHECK_XFEATURE(xfeature_nr);
-
-	if (!xfeature_enabled(xfeature_nr)) {
-		WARN_ONCE(1, "Checking alignment of disabled xfeature %d\n",
-			  xfeature_nr);
-		return 0;
-	}
-
-	cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
-	/*
-	 * The value returned by ECX[1] indicates the alignment
-	 * of state component 'i' when the compacted format
-	 * of the extended region of an XSAVE area is used:
-	 */
-	return !!(ecx & 2);
-}
-
-/*
- * This function sets up offsets and sizes of all extended states in
- * xsave area. This supports both standard format and compacted format
- * of the xsave area.
- */
-static void __init setup_xstate_comp_offsets(void)
-{
-	unsigned int next_offset;
-	int i;
-
-	/*
-	 * The FP xstates and SSE xstates are legacy states. They are always
-	 * in the fixed offsets in the xsave area in either compacted form
-	 * or standard form.
-	 */
-	xstate_comp_offsets[XFEATURE_FP] = 0;
-	xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state,
-						     xmm_space);
-
-	if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) {
-		for_each_extended_xfeature(i, fpu_kernel_cfg.max_features)
-			xstate_comp_offsets[i] = xstate_offsets[i];
-		return;
-	}
-
-	next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
-
-	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
-		if (xfeature_is_aligned(i))
-			next_offset = ALIGN(next_offset, 64);
-
-		xstate_comp_offsets[i] = next_offset;
-		next_offset += xstate_sizes[i];
-	}
-}
-
-/*
- * Setup offsets of a supervisor-state-only XSAVES buffer:
- *
- * The offsets stored in xstate_comp_offsets[] only work for one specific
- * value of the Requested Feature BitMap (RFBM).  In cases where a different
- * RFBM value is used, a different set of offsets is required.  This set of
- * offsets is for when RFBM=xfeatures_mask_supervisor().
- */
-static void __init setup_supervisor_only_offsets(void)
-{
-	unsigned int next_offset;
-	int i;
-
-	next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE;
-
-	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
-		if (!xfeature_is_supervisor(i))
-			continue;
-
-		if (xfeature_is_aligned(i))
-			next_offset = ALIGN(next_offset, 64);
-
-		xstate_supervisor_only_offsets[i] = next_offset;
-		next_offset += xstate_sizes[i];
-	}
-}
-
 /*
  * Print out xstate component offsets and sizes
  */
@@ -360,7 +297,8 @@ static void __init print_xstate_offset_size(void)
 
 	for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) {
 		pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n",
-			 i, xstate_comp_offsets[i], i, xstate_sizes[i]);
+			i, xfeature_get_offset(fpu_kernel_cfg.max_features, i),
+			i, xstate_sizes[i]);
 	}
 }
 
@@ -419,7 +357,6 @@ static void __init setup_init_fpu_buf(void)
 	if (!boot_cpu_has(X86_FEATURE_XSAVE))
 		return;
 
-	setup_xstate_features();
 	print_xstate_features();
 
 	xstate_init_xcomp_bv(&init_fpstate.regs.xsave, fpu_kernel_cfg.max_features);
@@ -448,25 +385,6 @@ static void __init setup_init_fpu_buf(void)
 	fxsave(&init_fpstate.regs.fxsave);
 }
 
-static int xfeature_uncompacted_offset(int xfeature_nr)
-{
-	u32 eax, ebx, ecx, edx;
-
-	/*
-	 * Only XSAVES supports supervisor states and it uses compacted
-	 * format. Checking a supervisor state's uncompacted offset is
-	 * an error.
-	 */
-	if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) {
-		WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr);
-		return -1;
-	}
-
-	CHECK_XFEATURE(xfeature_nr);
-	cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx);
-	return ebx;
-}
-
 int xfeature_size(int xfeature_nr)
 {
 	u32 eax, ebx, ecx, edx;
@@ -644,29 +562,15 @@ static bool __init check_xstate_against_struct(int nr)
 
 static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted)
 {
-	unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+	unsigned int topmost = fls64(xfeatures) -  1;
-	int i;
+	unsigned int offset = xstate_offsets[topmost];
 
-	for_each_extended_xfeature(i, xfeatures) {
+	if (topmost <= XFEATURE_SSE)
-		/* Align from the end of the previous feature */
+		return sizeof(struct xregs_state);
-		if (xfeature_is_aligned(i))
+
-			size = ALIGN(size, 64);
+	if (compacted)
-		/*
+		offset = xfeature_get_offset(xfeatures, topmost);
-		 * In compacted format the enabled features are packed,
+	return offset + xstate_sizes[topmost];
-		 * i.e. disabled features do not occupy space.
-		 *
-		 * In non-compacted format the offsets are fixed and
-		 * disabled states still occupy space in the memory buffer.
-		 */
-		if (!compacted)
-			size = xfeature_uncompacted_offset(i);
-		/*
-		 * Add the feature size even for non-compacted format
-		 * to make the end result correct
-		 */
-		size += xfeature_size(i);
-	}
-	return size;
 }
 
 /*
@@ -935,6 +839,10 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
 
 	/* Enable xstate instructions to be able to continue with initialization: */
 	fpu__init_cpu_xstate();
+
+	/* Cache size, offset and flags for initialization */
+	setup_xstate_cache();
+
 	err = init_xstate_size();
 	if (err)
 		goto out_disable;
@@ -950,8 +858,6 @@ void __init fpu__init_system_xstate(unsigned int legacy_size)
 				  fpu_user_cfg.max_features);
 
 	setup_init_fpu_buf();
-	setup_xstate_comp_offsets();
-	setup_supervisor_only_offsets();
 
 	/*
 	 * Paranoia check whether something in the setup modified the
@@ -1006,13 +912,19 @@ void fpu__resume_cpu(void)
  */
 static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 {
-	if (!xfeature_enabled(xfeature_nr)) {
+	u64 xcomp_bv = xsave->header.xcomp_bv;
-		WARN_ON_FPU(1);
+
+	if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
+		return NULL;
+
+	if (cpu_feature_enabled(X86_FEATURE_XSAVES)) {
+		if (WARN_ON_ONCE(!(xcomp_bv & BIT_ULL(xfeature_nr))))
 			return NULL;
 	}
 
-	return (void *)xsave + xstate_comp_offsets[xfeature_nr];
+	return (void *)xsave + xfeature_get_offset(xcomp_bv, xfeature_nr);
 }
+
 /*
  * Given the xsave area and a state inside, this function returns the
  * address of the state.
@@ -1043,8 +955,9 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
 	 * We should not ever be requesting features that we
 	 * have not enabled.
 	 */
-	WARN_ONCE(!(fpu_kernel_cfg.max_features & BIT_ULL(xfeature_nr)),
+	if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr)))
-		  "get of unsupported state");
+		return NULL;
+
 	/*
 	 * This assumes the last 'xsave*' instruction to
 	 * have requested that 'xfeature_nr' be saved.
@@ -1625,6 +1538,9 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
 
 	/* Calculate the resulting kernel state size */
 	mask = permitted | requested;
+	/* Take supervisor states into account on the host */
+	if (!guest)
+		mask |= xfeatures_mask_supervisor();
 	ksize = xstate_calculate_size(mask, compacted);
 
 	/* Calculate the resulting user state size */
@@ -1639,7 +1555,7 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
 
 	perm = guest ? &fpu->guest_perm : &fpu->perm;
 	/* Pairs with the READ_ONCE() in xstate_get_group_perm() */
-	WRITE_ONCE(perm->__state_perm, requested);
+	WRITE_ONCE(perm->__state_perm, mask);
 	/* Protected by sighand lock */
 	perm->__state_size = ksize;
 	perm->__user_state_size = usize;

arch/x86/lib/iomem.c

@@ -22,7 +22,7 @@ static __always_inline void rep_movs(void *to, const void *from, size_t n)
 		     : "memory");
 }
 
-void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
+static void string_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
 {
 	if (unlikely(!n))
 		return;
@@ -38,9 +38,8 @@ void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
 	}
 	rep_movs(to, (const void *)from, n);
 }
-EXPORT_SYMBOL(memcpy_fromio);
 
-void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
+static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
 {
 	if (unlikely(!n))
 		return;
@@ -56,14 +55,64 @@ void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
 	}
 	rep_movs((void *)to, (const void *) from, n);
 }
+
+static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
+{
+	const volatile char __iomem *in = from;
+	char *out = to;
+	int i;
+
+	for (i = 0; i < n; ++i)
+		out[i] = readb(&in[i]);
+}
+
+static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
+{
+	volatile char __iomem *out = to;
+	const char *in = from;
+	int i;
+
+	for (i = 0; i < n; ++i)
+		writeb(in[i], &out[i]);
+}
+
+static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c)
+{
+	volatile char __iomem *mem = a;
+	int i;
+
+	for (i = 0; i < c; ++i)
+		writeb(b, &mem[i]);
+}
+
+void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
+{
+	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
+		unrolled_memcpy_fromio(to, from, n);
+	else
+		string_memcpy_fromio(to, from, n);
+}
+EXPORT_SYMBOL(memcpy_fromio);
+
+void memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
+{
+	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO))
+		unrolled_memcpy_toio(to, from, n);
+	else
+		string_memcpy_toio(to, from, n);
+}
 EXPORT_SYMBOL(memcpy_toio);
 
 void memset_io(volatile void __iomem *a, int b, size_t c)
 {
+	if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) {
+		unrolled_memset_io(a, b, c);
+	} else {
 		/*
 		 * TODO: memset can mangle the IO patterns quite a bit.
 		 * perhaps it would be better to use a dumb one:
 		 */
 		memset((void *)a, b, c);
 	}
+}
 EXPORT_SYMBOL(memset_io);

tools/testing/selftests/x86/amx.c

@@ -368,9 +368,16 @@ static void req_xtiledata_perm(void)
 
 static void validate_req_xcomp_perm(enum expected_result exp)
 {
-	unsigned long bitmask;
+	unsigned long bitmask, expected_bitmask;
 	long rc;
 
+	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
+	if (rc) {
+		fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
+	} else if (!(bitmask & XFEATURE_MASK_XTILECFG)) {
+		fatal_error("ARCH_GET_XCOMP_PERM returns XFEATURE_XTILECFG off.");
+	}
+
 	rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA);
 	if (exp == FAIL_EXPECTED) {
 		if (rc) {
@@ -383,10 +390,15 @@ static void validate_req_xcomp_perm(enum expected_result exp)
 		fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected failure.\n");
 	}
 
+	expected_bitmask = bitmask | XFEATURE_MASK_XTILEDATA;
+
 	rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask);
 	if (rc) {
 		fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc);
-	} else if (bitmask & XFEATURE_MASK_XTILE) {
+	} else if (bitmask != expected_bitmask) {
+		fatal_error("ARCH_REQ_XCOMP_PERM set a wrong bitmask: %lx, expected: %lx.\n",
+			    bitmask, expected_bitmask);
+	} else {
 		printf("\tARCH_REQ_XCOMP_PERM is successful.\n");
 	}
 }