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arm64: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling 

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 <ard.biesheuvel@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2018-02-06 17:56:15 +00:00 committed by Catalin Marinas
parent 6167ec5c91
commit f72af90c37
1 changed files with 18 additions and 2 deletions
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20
arch/arm64/kvm/hyp/hyp-entry.S
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@ -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>
@ -64,10 +65,11 @@ alternative_endif
lsr x0, x1, #ESR_ELx_EC_SHIFT
cmp x0, #ESR_ELx_EC_HVC64
ccmp x0, #ESR_ELx_EC_HVC32, #4, ne
b.ne el1_trap
mrs x1, vttbr_el2 // If vttbr is valid, the 64bit guest
cbnz x1, el1_trap // called HVC
mrs x1, vttbr_el2 // If vttbr is valid, the guest
cbnz x1, el1_hvc_guest // called HVC
/* Here, we're pretty sure the host called HVC. */
ldp x0, x1, [sp], #16
@ -100,6 +102,20 @@ alternative_endif
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:
/*
* x0: ESR_EC