[PATCH v4.4 38/45] arm64: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: 2019-06-14 03:13:35
Also in:
stable
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
From: Marc Zyngier <redacted> commit f72af90c3783d924337624659b43e2d36f1b36b4 upstream. We want SMCCC_ARCH_WORKAROUND_1 to be fast. As fast as possible. So let's intercept it as early as we can by testing for the function call number as soon as we've identified a HVC call coming from the guest. Tested-by: Ard Biesheuvel <redacted> Reviewed-by: Christoffer Dall <redacted> Signed-off-by: Marc Zyngier <redacted> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> [ v4.4: Made changes to hyp.S instead and fixed registers ] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- arch/arm64/kvm/hyp.S | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 8d3da858c257..8aa2ede8c999 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S@@ -15,6 +15,7 @@ * along with this program. If not, see <http://www.gnu.org/licenses/>. */ +#include <linux/arm-smccc.h> #include <linux/linkage.h> #include <asm/alternative.h>
@@ -974,10 +975,11 @@ el1_sync: // Guest trapped into EL2 lsr x2, x1, #ESR_ELx_EC_SHIFT cmp x2, #ESR_ELx_EC_HVC64 + ccmp x2, #ESR_ELx_EC_HVC32, #4, ne b.ne el1_trap - mrs x3, vttbr_el2 // If vttbr is valid, the 64bit guest - cbnz x3, el1_trap // called HVC + mrs x3, vttbr_el2 // If vttbr is valid, the guest + cbnz x3, el1_hvc_guest // called HVC /* Here, we're pretty sure the host called HVC. */ pop x2, x3
@@ -1003,6 +1005,20 @@ el1_sync: // Guest trapped into EL2 pop lr, xzr 2: eret +el1_hvc_guest: + /* + * Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1. + * The workaround has already been applied on the host, + * so let's quickly get back to the guest. We don't bother + * restoring x1, as it can be clobbered anyway. + */ + ldr x1, [sp] // Guest's x0 + eor w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1 + cbnz w1, el1_trap + mov x0, x1 + add sp, sp, #16 + eret + el1_trap: /* * x1: ESR
--
2.21.0.rc0.269.g1a574e7a288b
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