[PATCH] KVM: arm64: Sync SPSR_EL1 when injecting an exception into a pVM

[Fuad Tabba]

When pKVM injects a synchronous exception into a protected guest, it
re-enters without restoring the guest's EL1 sysregs and writes the EL1
exception registers to hardware by hand: ESR_EL1 and ELR_EL1, but not
SPSR_EL1. enter_exception64() sets SPSR_EL1 (the interrupted PSTATE)
only in memory, so the guest's handler reads a stale SPSR_EL1 and
restores the wrong PSTATE on eret.

Write SPSR_EL1 alongside the other exception registers.

Fixes: 6c30bfb18d0b ("KVM: arm64: Add handlers for protected VM System Registers")
Reported-by: sashiko <sashiko at sashiko.dev>
Signed-off-by: Fuad Tabba <tabba at google.com>
---
 arch/arm64/kvm/hyp/nvhe/sys_regs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/sys_regs.c b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
index 8c3fbb413a06..1a7d5cd16d72 100644
--- a/arch/arm64/kvm/hyp/nvhe/sys_regs.c
+++ b/arch/arm64/kvm/hyp/nvhe/sys_regs.c
@@ -268,6 +268,7 @@ static void inject_sync64(struct kvm_vcpu *vcpu, u64 esr)
 
 	write_sysreg_el1(esr, SYS_ESR);
 	write_sysreg_el1(read_sysreg_el2(SYS_ELR), SYS_ELR);
+	write_sysreg_el1(read_sysreg_el2(SYS_SPSR), SYS_SPSR);
 	write_sysreg_el2(*vcpu_pc(vcpu), SYS_ELR);
 	write_sysreg_el2(*vcpu_cpsr(vcpu), SYS_SPSR);
 }
-- 
2.54.0.1136.gdb2ca164c4-goog