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KVM: PPC: Align pt_regs in kvm_vcpu_arch structure

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The H_ENTER_NESTED hypercall receives as second parameter the address
of a region of memory containing the values for the nested guest
privileged registers. We currently use the pt_regs structure contained
within kvm_vcpu_arch for that end.

Most hypercalls that receive a memory address expect that region to
not cross a 4K page boundary. We would want H_ENTER_NESTED to follow
the same pattern so this patch ensures the pt_regs structure sits
within a page.

Note: the pt_regs structure is currently 384 bytes in size, so
aligning to 512 is sufficient to ensure it will not cross a 4K page
and avoids punching too big a hole in struct kvm_vcpu_arch.

Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Murilo Opsfelder Araújo <muriloo@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220624142712.790491-1-farosas@linux.ibm.com
This commit is contained in:
Fabiano Rosas 2022-06-24 11:27:12 -03:00 committed by Michael Ellerman
parent 0df01238b8
commit f5c847ea19
1 changed files with 5 additions and 1 deletions
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6
arch/powerpc/include/asm/kvm_host.h
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@ -523,7 +523,11 @@ struct kvm_vcpu_arch {
struct kvmppc_book3s_shadow_vcpu *shadow_vcpu;
#endif
struct pt_regs regs;
/*
* This is passed along to the HV via H_ENTER_NESTED. Align to
* prevent it crossing a real 4K page.
*/
struct pt_regs regs __aligned(512);
struct thread_fp_state fp;