diff --git a/README.md b/README.md
index e139f18..2948a12 100644
--- a/README.md
+++ b/README.md
@@ -86,13 +86,13 @@ sudo ./spectre-meltdown-checker.sh
 **CVE-2018-3640** rogue system register read (Variant 3a)
 
    - Impact: TBC
-   - Mitigation: TBC
+   - Mitigation: microcode update only
    - Performance impact of the mitigation: negligible
 
 **CVE-2018-3639** speculative store bypass (Variant 4)
 
    - Impact: software using JIT (no known exploitation against kernel)
-   - Mitigation: TBC
+   - Mitigation: microcode update + kernel update making possible for affected software to protect itself
    - Performance impact of the mitigation: low to medium
 
 ## Understanding what this script does and doesn't
diff --git a/spectre-meltdown-checker.sh b/spectre-meltdown-checker.sh
index 032c42f..90d9a9a 100755
--- a/spectre-meltdown-checker.sh
+++ b/spectre-meltdown-checker.sh
@@ -64,7 +64,7 @@ show_usage()
 		--batch nrpe		produce machine readable output formatted for NRPE
 		--batch prometheus      produce output for consumption by prometheus-node-exporter
 
-		--variant [1,2,3]	specify which variant you'd like to check, by default all variants are checked,
+		--variant [1,2,3,3a,4]	specify which variant you'd like to check, by default all variants are checked,
 					can be specified multiple times (e.g. --variant 2 --variant 3)
 		--hw-only		only check for CPU information, don't check for any variant
 		--no-hw			skip CPU information and checks, if you're inspecting a kernel not to be run on this host
@@ -309,7 +309,10 @@ is_cpu_vulnerable()
 		# https://www.amd.com/en/corporate/speculative-execution
 		variant1=vuln
 		variant2=vuln
-		[ -z "$variant3" ] && variant3=immune
+		[ -z "$variant3"  ] && variant3=immune
+		# https://www.amd.com/en/corporate/security-updates
+		# "We have not identified any AMD x86 products susceptible to the Variant 3a vulnerability in our analysis to-date."
+		[ -z "$variant3a" ] && variant3a=immune
 	elif [ "$cpu_vendor" = ARM ]; then
 		# ARM
 		# reference: https://developer.arm.com/support/security-update
@@ -950,7 +953,7 @@ parse_cpu_details()
 	fi
 
 	echo "$cpu_ucode" | grep -q ^0x && cpu_ucode_decimal=$(( cpu_ucode ))
-	ucode_found="model $cpu_model stepping $cpu_stepping ucode $cpu_ucode cpuid "$(printf "0x%x" "$cpuid")
+	ucode_found=$(printf "model 0x%x family 0x%x stepping 0x%x ucode 0x%x cpuid 0x%x" "$cpu_model" "$cpu_family" "$cpu_stepping" "$cpu_ucode" "$cpuid")
 
 	# also define those that we will need in other funcs
 	# taken from ttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/include/asm/intel-family.h
@@ -1669,16 +1672,43 @@ check_cpu()
 	fi
 
 	# variant 4
-	_info     "  * Speculative Store Bypass Disable (SSBD)"
-	_info_nol "    * CPU indicates SSBD capability: "
-	read_cpuid 0x7 $EDX 31 1 1; ret=$?
-	if [ $ret -eq 0 ]; then
-		#cpuid_ng1=1
-		pstatus green YES "SSBD feature bit"
-	elif [ $ret -eq 1 ]; then
-		pstatus yellow NO
-	else
+	if is_intel; then
+		_info     "  * Speculative Store Bypass Disable (SSBD)"
+		_info_nol "    * CPU indicates SSBD capability: "
+		read_cpuid 0x7 $EDX 31 1 1; ret=$?
+		if [ $ret -eq 0 ]; then
+			cpuid_ssbd='Intel SSBD'
+		fi
+	elif is_amd; then
+		_info     "  * Speculative Store Bypass Disable (SSBD)"
+		_info_nol "    * CPU indicates SSBD capability: "
+		read_cpuid 0x80000008 $EBX 24 1 1; ret24=$?
+		read_cpuid 0x80000008 $EBX 25 1 1; ret25=$?
+		if [ $ret24 -eq 0 ]; then
+			cpuid_ssbd='AMD SSBD in SPEC_CTRL'
+			#cpuid_ssbd_spec_ctrl=1
+		elif [ $ret25 -eq 0 ]; then
+			cpuid_ssbd='AMD SSBD in VIRT_SPEC_CTRL'
+			#cpuid_ssbd_virt_spec_ctrl=1
+		elif [ "$cpu_family" -ge 21 ] && [ "$cpu_family" -le 23 ]; then
+			cpuid_ssbd='AMD non-architectural MSR'
+		fi
+	fi
+
+	if [ -n "$cpuid_ssbd" ]; then
+		pstatus green YES "$cpuid_ssbd"
+	elif [ "$ret24" = 2 ] && [ "$ret25" = 2 ]; then
 		pstatus yellow UNKNOWN "is cpuid kernel module available?"
+	else
+		pstatus yellow NO
+	fi
+
+	if is_amd; then
+		# similar to SSB_NO for intel
+		read_cpuid 0x80000008 $EBX 26 1 1; ret=$?
+		if [ $ret -eq 0 ]; then
+			amd_ssb_no=1
+		fi
 	fi
 
 	if is_intel; then
@@ -1765,15 +1795,15 @@ check_cpu()
 		else
 			pstatus yellow NO
 		fi
+	fi
 
-		_info_nol "  * CPU explicitly indicates not being vulnerable to Variant 4 (SSB_NO): "
-		if [ "$capabilities_ssb_no" = -1 ]; then
-			pstatus yellow UNKNOWN
-		elif [ "$capabilities_ssb_no" = 1 ]; then
-			pstatus green YES
-		else
-			pstatus yellow NO
-		fi
+	_info_nol "  * CPU explicitly indicates not being vulnerable to Variant 4 (SSB_NO): "
+	if [ "$capabilities_ssb_no" = -1 ]; then
+		pstatus yellow UNKNOWN
+	elif [ "$capabilities_ssb_no" = 1 ] || [ "$amd_ssb_no" = 1 ]; then
+		pstatus green YES
+	else
+		pstatus yellow NO
 	fi
 
 	_info_nol "  * CPU microcode is known to cause stability problems: "
@@ -2102,7 +2132,7 @@ check_variant2_linux()
 			fi
 			if [ -e "/sys/devices/system/cpu/vulnerabilities/spectre_v2" ]; then
 				# when IBPB is enabled on 4.15+, we can see it in sysfs
-				if grep -q ', IBPB' "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
+				if grep -q 'IBPB' "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
 					_debug "ibpb: found enabled in sysfs"
 					[ -z "$ibpb_supported" ] && ibpb_supported='IBPB found enabled in sysfs'
 					[ -z "$ibpb_enabled"   ] && ibpb_enabled=1
@@ -2114,7 +2144,7 @@ check_variant2_linux()
 					ibrs_fw_enabled=1
 				fi
 				# when IBRS is enabled on 4.15+, we can see it in sysfs
-				if grep -q 'Indirect Branch Restricted Speculation' "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
+				if grep -q -e 'IBRS' -e 'Indirect Branch Restricted Speculation' "/sys/devices/system/cpu/vulnerabilities/spectre_v2"; then
 					_debug "ibrs: found IBRS in sysfs"
 					[ -z "$ibrs_supported" ] && ibrs_supported='found IBRS in sysfs'
 					[ -z "$ibrs_enabled"   ] && ibrs_enabled=3
@@ -2886,12 +2916,28 @@ check_variant3a()
 {
 	_info "\033[1;34mCVE-2018-3640 [rogue system register read] aka 'Variant 3a'\033[0m"
 
+	status=UNK
+	sys_interface_available=0
+	msg=''
+
+	_info_nol "  * CPU microcode mitigates the vulnerability: "
+	if [ -n "$cpuid_ssbd" ]; then
+		# microcodes that ship with SSBD are known to also fix variant3a
+		# there is no specific cpuid bit as far as we know
+		pstatus green YES
+	else
+		pstatus yellow NO
+	fi
+
 	cve='CVE-2018-3640'
 	if ! is_cpu_vulnerable 3a; then
 		# override status & msg in case CPU is not vulnerable after all
 		pvulnstatus $cve OK "your CPU vendor reported your CPU model as not vulnerable"
+	elif [ -n "$cpuid_ssbd" ]; then
+		pvulnstatus $cve OK "your CPU microcode mitigates the vulnerability"
 	else
-		pvulnstatus $cve UNK "new vulnerability, script will be updated when more technical information is available in the next hours/days"
+		pvulnstatus $cve VULN "an up-to-date CPU microcode is needed to mitigate this vulnerability"
+		explain "The microcode of your CPU needs to be upgraded to mitigate this vulnerability. This is usually done at boot time by your kernel (the upgrade is not persistent across reboots which is why it's done at each boot). If you're using a distro, make sure you are up to date, as microcode updates are usually shipped alongside with the distro kernel. Availability of a microcode update for you CPU model depends on your CPU vendor. You can usually find out online if a microcode update is available for your CPU by searching for your CPUID (indicated in the Hardware Check section). The microcode update is enough, there is no additional OS, kernel or software change needed."
 	fi
 }
 
@@ -2899,12 +2945,66 @@ check_variant4()
 {
 	_info "\033[1;34mCVE-2018-3639 [speculative store bypass] aka 'Variant 4'\033[0m"
 
+	status=UNK
+	sys_interface_available=0
+	msg=''
+	if sys_interface_check "/sys/devices/system/cpu/vulnerabilities/spec_store_bypass"; then
+		# this kernel has the /sys interface, trust it over everything
+		sys_interface_available=1
+	fi
+	if [ "$opt_sysfs_only" != 1 ]; then
+		_info_nol "  * Kernel supports speculation store bypass: "
+		if [ "$opt_live" = 1 ]; then
+			if grep -Eq 'Speculation.?Store.?Bypass:' /proc/self/status 2>/dev/null; then
+				kernel_ssb='found in /proc/self/status'
+				_debug "found Speculation.Store.Bypass: in /proc/self/status"
+			fi
+		fi
+		if [ -z "$kernel_ssb" ] && [ -n "$kernel" ]; then
+			kernel_ssb=$("${opt_arch_prefix}strings" "$kernel" | grep spec_store_bypass | head -n1);
+			[ -n "$kernel_ssb" ] && _debug "found $kernel_ssb in kernel"
+		fi
+		if [ -z "$kernel_ssb" ] && [ -n "$opt_map" ]; then
+			kernel_ssb=$(grep spec_store_bypass "$opt_map" | head -n1)
+			[ -n "$kernel_ssb" ] && _debug "found $kernel_ssb in System.map"
+		fi
+
+		if [ -n "$kernel_ssb" ]; then
+			pstatus green YES "$kernel_ssb"
+		else
+			pstatus yellow NO
+		fi
+
+	elif [ "$sys_interface_available" = 0 ]; then
+		# we have no sysfs but were asked to use it only!
+		msg="/sys vulnerability interface use forced, but it's not available!"
+		status=UNK
+	fi
+
 	cve='CVE-2018-3639'
 	if ! is_cpu_vulnerable 4; then
 		# override status & msg in case CPU is not vulnerable after all
 		pvulnstatus $cve OK "your CPU vendor reported your CPU model as not vulnerable"
+	elif [ -z "$msg" ] || [ "$msg" = "Vulnerable" ]; then
+		# if msg is empty, sysfs check didn't fill it, rely on our own test
+		if [ -n "$cpuid_ssbd" ]; then
+			if [ -n "$kernel_ssb" ]; then
+				pvulnstatus $cve OK "your system provides the necessary tools for software mitigation"
+			else
+				pvulnstatus $cve VULN "your kernel needs to be updated"
+				explain "You have a recent-enough CPU microcode but your kernel is too old to use the new features exported by your CPU's microcode. If you're using a distro kernel, upgrade your distro to get the latest kernel available. Otherwise, recompile the kernel from recent-enough sources."
+			fi
+		else
+			if [ -n "$kernel_ssb" ]; then
+				pvulnstatus $cve VULN "Your CPU doesn't support SSBD"
+				explain "Your kernel is recent enough to use the CPU microcode features for mitigation, but your CPU microcode doesn't actually provide the necessary features for the kernel to use. The microcode of your CPU hence needs to be upgraded. This is usually done at boot time by your kernel (the upgrade is not persistent across reboots which is why it's done at each boot). If you're using a distro, make sure you are up to date, as microcode updates are usually shipped alongside with the distro kernel. Availability of a microcode update for you CPU model depends on your CPU vendor. You can usually find out online if a microcode update is available for your CPU by searching for your CPUID (indicated in the Hardware Check section)."
+			else
+				pvulnstatus $cve VULN "Neither your CPU nor your kernel support SSBD"
+				explain "Both your CPU microcode and your kernel are lacking support for mitigation. If you're using a distro kernel, upgrade your distro to get the latest kernel available. Otherwise, recompile the kernel from recent-enough sources. The microcode of your CPU also needs to be upgraded. This is usually done at boot time by your kernel (the upgrade is not persistent across reboots which is why it's done at each boot). If you're using a distro, make sure you are up to date, as microcode updates are usually shipped alongside with the distro kernel. Availability of a microcode update for you CPU model depends on your CPU vendor. You can usually find out online if a microcode update is available for your CPU by searching for your CPUID (indicated in the Hardware Check section)."
+			fi
+		fi
 	else
-		pvulnstatus $cve UNK "new vulnerability, script will be updated when more technical information is available in the next hours/days"
+		pvulnstatus $cve "$status" "$msg"
 	fi
 }