Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1319487

[PATCH 3.14 51/59] arm64: KVM: Fix AArch32 to AArch64 register mapping

Show all headers | View raw

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit c0f0963464c24e034b858441205455bf2a5d93ad upstream.

When running a 32bit guest under a 64bit hypervisor, the ARMv8
architecture defines a mapping of the 32bit registers in the 64bit
space. This includes banked registers that are being demultiplexed
over the 64bit ones.

On exceptions caused by an operation involving a 32bit register, the
HW exposes the register number in the ESR_EL2 register. It was so
far understood that SW had to distinguish between AArch32 and AArch64
accesses (based on the current AArch32 mode and register number).

It turns out that I misinterpreted the ARM ARM, and the clue is in
D1.20.1: "For some exceptions, the exception syndrome given in the
ESR_ELx identifies one or more register numbers from the issued
instruction that generated the exception. Where the exception is
taken from an Exception level using AArch32 these register numbers
give the AArch64 view of the register."

Which means that the HW is already giving us the translated version,
and that we shouldn't try to interpret it at all (for example, doing
an MMIO operation from the IRQ mode using the LR register leads to
very unexpected behaviours).

The fix is thus not to perform a call to vcpu_reg32() at all from
vcpu_reg(), and use whatever register number is supplied directly.
The only case we need to find out about the mapping is when we
actively generate a register access, which only occurs when injecting
a fault in a guest.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/include/asm/kvm_emulate.h |    8 +++++---
 arch/arm64/kvm/inject_fault.c        |    2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)

--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -86,11 +86,13 @@ static inline void vcpu_set_thumb(struct
 	*vcpu_cpsr(vcpu) |= COMPAT_PSR_T_BIT;
 }
 
+/*
+ * vcpu_reg should always be passed a register number coming from a
+ * read of ESR_EL2. Otherwise, it may give the wrong result on AArch32
+ * with banked registers.
+ */
 static inline unsigned long *vcpu_reg(const struct kvm_vcpu *vcpu, u8 reg_num)
 {
-	if (vcpu_mode_is_32bit(vcpu))
-		return vcpu_reg32(vcpu, reg_num);
-
 	return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.regs[reg_num];
 }
 
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -48,7 +48,7 @@ static void prepare_fault32(struct kvm_v
 
 	/* Note: These now point to the banked copies */
 	*vcpu_spsr(vcpu) = new_spsr_value;
-	*vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
+	*vcpu_reg32(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
 
 	/* Branch to exception vector */
 	if (sctlr & (1 << 13))

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 3.14 00/59] 3.14.60-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 18/59] ALSA: timer: Fix double unlink of active_list Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 42/59] ipv6: update skb->csum when CE mark is propagated Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 45/59] team: Replace rcu_read_lock with a mutex in team_vlan_rx_kill_vid Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 05/59] x86/reboot/quirks: Add iMac10,1 to pci_reboot_dmi_table[] Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 08/59] ALSA: hda - Add Intel Lewisburg device IDs Audio Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 22/59] ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 02/59] xen/gntdev: Grant maps should not be subject to NUMA balancing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 03/59] x86/xen: dont reset vcpu_info on a cancelled suspend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 27/59] usb: xhci: fix config fail of FS hub behind a HS hub with MTT Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 26/59] ASoC: compress: Fix compress device direction check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 24/59] ASoC: wm8974: set cache type for regmap Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 40/59] bonding: Prevent IPv6 link local address on enslaved devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 21/59] ALSA: hrtimer: Fix stall by hrtimer_cancel() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 07/59] ipmi: move timer init to before irq is setup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 41/59] phonet: properly unshare skbs in phonet_rcv() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 04/59] KVM: PPC: Book3S HV: Prohibit setting illegal transaction state in MSR Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 20/59] ALSA: pcm: Fix snd_pcm_hw_params struct copy in compat mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 28/59] USB: ipaq.c: fix a timeout loop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 30/59] xhci: refuse loading if nousb is used Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 52/59] arm64: fix building without CONFIG_UID16 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 19/59] ALSA: seq: Fix snd_seq_call_port_info_ioctl in compat mode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 09/59] ALSA: hda - Apply pin fixup for HP ProBook 6550b Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 53/59] arm64: Clear out any singlestep state on a ptrace detach operation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 49/59] powerpc: Make {cmp}xchg* and their atomic_ versions fully ordered Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 43/59] isdn_ppp: Add checks for allocation failure in isdn_ppp_open() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 39/59] tcp_yeah: dont set ssthresh below 2 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 46/59] powerpc/tm: Block signal return setting invalid MSR state Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 06/59] x86/boot: Double BOOT_HEAP_SIZE to 64KB Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 51/59] arm64: KVM: Fix AArch32 to AArch64 register mapping Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:30 +0100
  [PATCH 3.14 11/59] ALSA: hda - Add inverted dmic for Packard Bell DOTS Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 14/59] ALSA: seq: Fix missing NULL check at remove_events ioctl Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 23/59] ASoC: wm8962: correct addresses for HPF_C_0/1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 16/59] ALSA: timer: Harden slave timer list handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 17/59] ALSA: timer: Fix race among timer ioctls Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 25/59] ASoC: arizona: Fix bclk for sample rates that are multiple of 4kHz Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 10/59] ALSA: rme96: Fix unexpected volume reset after rate changes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 13/59] ALSA: hda/realtek - Fix silent headphone output on MacPro 4,1 (v2) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 01/59] x86/signal: Fix restart_syscall number for x32 tasks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 12/59] ALSA: hda - Set SKL+ hda controller power at freeze() and thaw() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 15/59] ALSA: seq: Fix race at timer setup and close Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 20:40 +0100
  [PATCH 3.14 32/59] ipv6/addrlabel: fix ip6addrlbl_get() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:00 +0100
  [PATCH 3.14 59/59] arm64: restore bogomips information in /proc/cpuinfo Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:00 +0100
  [PATCH 3.14 38/59] net: sctp: prevent writes to cookie_hmac_alg from accessing invalid memory Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:00 +0100
  [PATCH 3.14 29/59] USB: cp210x: add ID for ELV Marble Sound Board 1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 35/59] unix: properly account for FDs passed over unix sockets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 34/59] connector: bump skb->users before callback invocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 36/59] bridge: Only call /sbin/bridge-stp for the initial network namespace Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 58/59] mn10300: Select CONFIG_HAVE_UID16 to fix build failure Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 37/59] net: possible use after free in dst_release Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100
  [PATCH 3.14 33/59] sctp: sctp should release assoc when sctp_make_abort_user return NULL in sctp_close Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-01-27 21:10 +0100

csiph-web