This is a note to let you know that I've just added the patch titled

KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-arm-arm64-vgic-fix-command-handling-while-its-being-disabled.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Tue Dec 12 13:26:17 CET 2017

From: Andre Przywara andre.przywara@arm.com Date: Thu, 16 Feb 2017 10:41:20 +0000 Subject: KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled

From: Andre Przywara andre.przywara@arm.com

[ Upstream commit a5e1e6ca94a8cec51571fd62e3eaec269717969c ]

The ITS spec says that ITS commands are only processed when the ITS is enabled (section 8.19.4, Enabled, bit[0]). Our emulation was not taking this into account. Fix this by checking the enabled state before handling CWRITER writes.

On the other hand that means that CWRITER could advance while the ITS is disabled, and enabling it would need those commands to be processed. Fix this case as well by refactoring actual command processing and calling this from both the GITS_CWRITER and GITS_CTLR handlers.

Reviewed-by: Eric Auger eric.auger@redhat.com Reviewed-by: Christoffer Dall cdall@linaro.org Signed-off-by: Andre Przywara andre.przywara@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/arm/vgic/vgic-its.c | 109 +++++++++++++++++++++++++------------------ 1 file changed, 65 insertions(+), 44 deletions(-)

--- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -360,29 +360,6 @@ static int its_sync_lpi_pending_table(st return ret; }

-static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu, - struct vgic_its *its, - gpa_t addr, unsigned int len) -{ - u32 reg = 0; - - mutex_lock(&its->cmd_lock); - if (its->creadr == its->cwriter) - reg |= GITS_CTLR_QUIESCENT; - if (its->enabled) - reg |= GITS_CTLR_ENABLE; - mutex_unlock(&its->cmd_lock); - - return reg; -} - -static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its, - gpa_t addr, unsigned int len, - unsigned long val) -{ - its->enabled = !!(val & GITS_CTLR_ENABLE); -} - static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm, struct vgic_its *its, gpa_t addr, unsigned int len) @@ -1162,33 +1139,16 @@ static void vgic_mmio_write_its_cbaser(s #define ITS_CMD_SIZE 32 #define ITS_CMD_OFFSET(reg) ((reg) & GENMASK(19, 5))

-/* - * By writing to CWRITER the guest announces new commands to be processed. - * To avoid any races in the first place, we take the its_cmd lock, which - * protects our ring buffer variables, so that there is only one user - * per ITS handling commands at a given time. - */ -static void vgic_mmio_write_its_cwriter(struct kvm *kvm, struct vgic_its *its, - gpa_t addr, unsigned int len, - unsigned long val) +/* Must be called with the cmd_lock held. */ +static void vgic_its_process_commands(struct kvm *kvm, struct vgic_its *its) { gpa_t cbaser; u64 cmd_buf[4]; - u32 reg;

- if (!its) - return; - - mutex_lock(&its->cmd_lock); - - reg = update_64bit_reg(its->cwriter, addr & 7, len, val); - reg = ITS_CMD_OFFSET(reg); - if (reg >= ITS_CMD_BUFFER_SIZE(its->cbaser)) { - mutex_unlock(&its->cmd_lock); + /* Commands are only processed when the ITS is enabled. */ + if (!its->enabled) return; - }

- its->cwriter = reg; cbaser = CBASER_ADDRESS(its->cbaser);

while (its->cwriter != its->creadr) { @@ -1208,6 +1168,34 @@ static void vgic_mmio_write_its_cwriter( if (its->creadr == ITS_CMD_BUFFER_SIZE(its->cbaser)) its->creadr = 0; } +} + +/* + * By writing to CWRITER the guest announces new commands to be processed. + * To avoid any races in the first place, we take the its_cmd lock, which + * protects our ring buffer variables, so that there is only one user + * per ITS handling commands at a given time. + */ +static void vgic_mmio_write_its_cwriter(struct kvm *kvm, struct vgic_its *its, + gpa_t addr, unsigned int len, + unsigned long val) +{ + u64 reg; + + if (!its) + return; + + mutex_lock(&its->cmd_lock); + + reg = update_64bit_reg(its->cwriter, addr & 7, len, val); + reg = ITS_CMD_OFFSET(reg); + if (reg >= ITS_CMD_BUFFER_SIZE(its->cbaser)) { + mutex_unlock(&its->cmd_lock); + return; + } + its->cwriter = reg; + + vgic_its_process_commands(kvm, its);

mutex_unlock(&its->cmd_lock); } @@ -1288,6 +1276,39 @@ static void vgic_mmio_write_its_baser(st *regptr = reg; }

+static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu, + struct vgic_its *its, + gpa_t addr, unsigned int len) +{ + u32 reg = 0; + + mutex_lock(&its->cmd_lock); + if (its->creadr == its->cwriter) + reg |= GITS_CTLR_QUIESCENT; + if (its->enabled) + reg |= GITS_CTLR_ENABLE; + mutex_unlock(&its->cmd_lock); + + return reg; +} + +static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its, + gpa_t addr, unsigned int len, + unsigned long val) +{ + mutex_lock(&its->cmd_lock); + + its->enabled = !!(val & GITS_CTLR_ENABLE); + + /* + * Try to process any pending commands. This function bails out early + * if the ITS is disabled or no commands have been queued. + */ + vgic_its_process_commands(kvm, its); + + mutex_unlock(&its->cmd_lock); +} + #define REGISTER_ITS_DESC(off, rd, wr, length, acc) \ { \ .reg_offset = off, \

Patches currently in stable-queue which might be from andre.przywara@arm.com are

queue-4.9/kvm-arm-arm64-vgic-fix-command-handling-while-its-being-disabled.patch